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Video Viewing in Lion Freezes New iMacs

I’m generally pretty fortunate when upgrading to new versions of Mac OS X. While I often see people lamenting in forums how this or that feature doesn’t work, how a certain program is broken, or how they have hardware problems following an upgrade, that’s never happened to me. Until now.

I have a new 27-inch iMac, purchased in June 2011. It worked perfectly with Mac OS X 10.6 Snow Leopard, but when I upgraded to 10.7 Lion, I started having problems with the computer freezing when I viewed videos. This occurs with all kinds of videos: Flash, H.264, and QuickTime formats, as well as AVIs and MKVs. And we’re talking about a serious freeze: the entire screen freezes, except for the cursor. Music may continue playing if iTunes is running, but the only way to resolve the problem is to force a shutdown by pressing and holding the power button. Interestingly, these video-related problems occur only after the Mac has been put to sleep. If I restart the iMac, the freeze won’t happen until it’s put to sleep, then awakened.

There is information in the kernel.log that strongly suggests that this is a problem with either the video card (GPU) or its drivers:

7/23/11 12:02:40.000 PM kernel: ** GPU Debug Info Start ** 7/23/11 12:02:40.000 PM kernel: 0x00006740 7/23/11 12:02:40.000 PM kernel: 0x0000008f 7/23/11 12:02:40.000 PM kernel: 0x00000001 7/23/11 12:02:40.000 PM kernel: 0x00000018 7/23/11 12:02:40.000 PM kernel: 0x0000a880 [and so on for a few hundred lines]

This problem seems to have hit thousands of Mac users, and while Apple is trying to find a solution, they haven’t yet, leading to an increasing level of ire among some of those affected. There is, as of this writing, a 50-page thread on the Apple Discussions forum lamenting this issue, and I’ve been chronicling it on my blog, where I also posted a screenshot of a Quick Look window showing the video problem just seconds before a freeze.

How It Began -- I first noticed this problem shortly after the Lion GM (golden master) was released. I have a developer account, and had been running developer preview releases of Lion on my secondary Mac, a 2010 MacBook Air, with no major issues. When the GM was released to developers, I decided to install it on my iMac as well. I experienced several freezes early on, but since Lion was still not officially released, it wasn’t easy to find other users with the problem to know if it was common. I did find one, however, in fellow TidBITS and Take Control author Michael Cohen, who had also recently bought a new iMac. On the super-secret mailing list for Take Control authors, he mentioned the problem, and I said that I was having it as well. A quick email conversation confirmed that it was exactly the same.

Trying to Fix the Problem -- Even though I have a new iMac, and had already purchased AppleCare, I knew I couldn’t contact Apple about this; they would say that I was running pre-release software and there was nothing they could do. I avoided watching any videos, and, finally, on 23 July 2011, after Lion was released, called Apple Support.

I explained the problem, and got a very understanding support technician, who did not waste my time asking me to reset the PRAM and SMC (which I had already done), or reinstall Lion. I made it clear that there had been no problems with Snow Leopard, and it was unlikely that it was the iMac that was at cause. He took notes and said he’d get back to me.

A few days later, to my surprise, I got a call from a senior tech support engineer. My case had quickly been escalated, because the support staff clearly realized that this was a serious issue. I explained what had happened and what I had done to try and resolve it, and he offered several possible solutions. I deleted certain cache folders, and sent him some logs; he called back again, asking me to try disconnecting peripherals (check), removing third-party RAM (check), and, finally, to do a clean installation on a different disk (check). The problem still occurred, though it took me a while to reproduce it following the clean installation.

What’s Next? -- As of now, there is no solution. I know Apple is working hard to find the cause, as I’ve been in regular contact with support engineers by email and telephone. While the sprawling Apple forum thread is difficult to navigate, and many people think they have found solutions (which turn out to be transitory), here’s the lowdown.

Viewing videos of any kind on new iMacs, both the 21.5-inch and 27-inch models, can cause freezes. This doesn’t happen every time one views a video, and happens only after an iMac has been put to sleep at least once. These videos can be Flash, H.264, or QuickTime formats, and viewing may occur in Safari, Firefox, QuickTime Player, iTunes or any other program.

The usual troubleshooting steps, such as resetting the PRAM and SMC, are ineffective. Similarly, a clean installation of Lion, with no third-party software installed, does not solve the problem. Deleting and/or reinstalling Flash and Java, both suggestions floated in the Apple forum, has no effect. Fiddling with RAM or other hardware makes no difference, though it may turn out that this is a hardware problem with video cards. (A specific video card bug seems unlikely, though, because many people with this problem, including myself, bought their iMacs with Snow Leopard, and did not have freezes until upgrading to Lion — the problem seems to be a conflict between the iMac’s video card and Lion.) In short, none of the “solutions” offered on the Apple forums resolve the issue.

If you have this problem, there are only two ways to avoid it:

  • Don’t watch videos, if possible, or do so only after restarting your iMac.

  • Instead of putting your iMac to sleep at night, shut it down. With Lion’s Resume feature, particularly on an SSD-equipped iMac, starting fresh shouldn’t take long, and avoiding sleep seems to be the one sure way of sidestepping the freezes. Obviously, you could leave your iMac on all the time, but that’s a waste of electricity.

Also, please, if you have this problem, contact Apple Support, so they know how many people are affected. Tell them what you’ve read, here and on the Apple forums, and try not to waste your time if they ask you to do anything complicated that has been proven to be ineffective, such as reinstalling Lion.

I’d like to give Apple a bye on this problem, but it’s disappointing to think that in their testing of Lion, they didn’t spot it, particularly with the newest iMacs. I know that if they had found a solution, I would have heard from the support technicians I’ve been in contact with, and I’m hopeful that they find the cause soon and issue a fix.

Operating systems are complex, and the types of problems that can occur are many. At least, in cases like this, there are relatively few hardware variables, as there would be with Windows PCs; new iMacs have one of only three different video cards.

But a lot of iMac users — and, judging from the Apple forum thread, many of whom are new to Macs — are very angry that this is happening with brand new Macs. As for me, I take it as just another bump in the road. I don’t watch a lot of videos on my iMac, but if I needed to for my work, I would probably be somewhat less stoic.

Finally, if you have a new iMac that’s still running Snow Leopard, and you watch videos of any sort, I recommend holding off on a Lion upgrade until Apple addresses this conflict.

[Kirk McElhearn is a Senior Contributor to Macworld and an occasional contributor to TidBITS, and he writes about more than just Macs on his blog Kirkville. Kirk’s latest book is “Take Control of Scrivener 2.” Follow him on Twitter at @mcelhearn.]


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Comments about Video Viewing in Lion Freezes New iMacs
(Comments are closed.)

Great run down of the problem. Like you, I trust that Apple will find the answer soon and I can be patient. It is a serious issue, but the sky won't fall if I have to wait a week or so for it to get fixed. Am I disappointed? Absolutely. But this stuff happens. What I worry about are the newcomers getting a bad taste in their mouth. But as I remember, the iPhone 4 had a major issue with the antenna, Apple came clean and all is well with the world. This too will pass.
My previous 24" iMac would exhibit this exact behavior while playing videos. Ultimately it was diagnosed to be an overheating power source and graphics card. It's possible Lion has altered fan behavior on this generation of hardware, causing the internal boards to get too warm under GPU load.
No, it's not a temperature issue; I've checked that.
uhuznaa  2011-08-04 13:41
There are other problems with 10.7.0, many people with portable Macs have drastically decreased battery life.

I'm sticking with SL at least until 10.7.1 ...
Michael E. Cohen  An apple icon for a TidBITS Staffer 2011-08-04 15:28
My experience with this issue may be idiosyncratic, but I have found that I'm much more likely to have the freeze occur if I have iTunes running when I play a video (even if it isn't iTunes playing the video). If I make sure to quit iTunes before playing a video with QuickTime or Safari, the freeze happens much less--only once in the past week. So, iTunes may contribute to the problem, but isn't the source of it.

Thanks, Kirk, for publicizing this issue.
Robert Hancock  2011-08-04 17:29
Don't forget the other MAJOR problem with 10.7—wifi dropouts. Almost 30 pages at ASC, 30,000 visits and now a Facebook page. Since Lion relies so heavily on net connectivity for recovery, installs, etc., this is a real show stopper for a lot of folks. No public admission from Apple that anything is wrong either.
Yes, I've been having problems with that. It is not, however, easily reproducible. And in my case, it only happens every few days.
I also have the related "return from sleep issue" of losing wireles connectivity. I've switched to Ethernet and all is well. Combine this of course with the fact that I also have one of the defective hard drives and you got the trifecta of goodiesnto send in for repair.
Although I have had the video dropout problem as described, I also have had good luck watching video podcasts in iTunes and videos on HBO Go in the browser.
Jim Huls  2011-08-05 13:07
I have a thunderbolt iMac model(27") but have yet to see this problem.

I have seen where sometimes the system will not let me log back in when it comes out of sleep. The curser moves but I cannot type in my password. I've also had this happen on my 2008 unibody MBPro. On each machine it's happened 2-3 times in the last week. I do run various 3rd party apps so I'm not ruling out something's just a PIA to come up with time to troubleshoot what might be a Lion patch needed.
Jim murphy  2011-08-05 15:18
Thanks Kirk I have this problem but it will not let me restart for anything to 5 minutes to 14hours, is anyone else having this problem?
I haven't seen that, nor read about anyone else with a similar problem. How does it not let you restart?
Steve Self   2011-08-05 21:26
I have a 10 day old i7 iMac... It freezes 2-3 times a day. Not just with video playing. Sometimes just typing. Though I do run a lot of apps... But that is why the i7 and 8 GB ram. Hard to believe this did not show up in testing. But so it goes. Sure hope there is a fix soon. Otherwise I take it back for a refund...
Robert Latzer  2011-08-06 19:31
I have had this problem since OS X 10.6.3
It's still happening with Lion. I have had the computer checked thoroughly. I have been following the thread on the Apple support groups site. And nothing that has been suggested has worked for me. I am glad you are keeping tabs on this and I hope you can be of influence. Apple is ignoring me at this point.
If you've had the problem since 10.6.3, I'm guessing it's a different cause. Because almost everyone in the Gargantuan Apple forum thread has a new iMac which worked fine under Snow. I wish I had an answer, but it's likely that in your case it's a hardware problem. Is your Mac under guarantee?
Robert Latzer  2011-08-07 08:52
Yes my iMac which is 2 years old is still under warranty. I have had the graphics card replaced already which didn't help. Many users have had the freezing display problem since 10.6.3 as shown in the discussion thread. My mac passed all hardware tests. Apple told me they are unaware of the comments in the Apple forum!!!
I have this same problem with a 2 year old iMac. The display suddenly goes blank - sometimes all black, all white, or striped and I have to manually power down. I've reported it a number of times to AppleCare. Unfortunately, it occurs randomly every few months and they don't seem to have any clue how to deal with it. I pointed out the over 50 page long discussion in my last call but it didn't see to make an impression.
There are reports that the 10.7.2 beta, available to developers, resolves the problem. Personally, I'm not comfortable putting a beta on my main Mac, so I won't be trying it. But this suggests that the problem was solved some time ago, as 10.7.2 has apparently been available for a while. This said, when I log into my developer account, I don't see it...
Benjamin Lowengard  2011-08-07 08:27
Sort of a sidebar here, but apparently Flash causes some Audioio issues causing audio to drop out until it's reset. I use a presous firebox and indeed after i view some flash stuff my Audioio quits and i have to reset my (audio) clock settings to get Audio back on.
Matt Neuburg  An apple icon for a TidBITS Staffer 2011-08-08 17:57
According to this story, MacBook Pro owners with nVidia graphics cards are also having panics, under somewhat similar circumstances:

And again, this was known and reported but not fixed during the beta period. Makes one wonder what a beta period is for.
Stuart  2011-08-08 18:58
Obviously, what Apple needs to do is

Oops, there I go forgetting myself.
thevoiceoverguy  2011-08-10 05:57
Would be curious to know, since we all have different hardware, if all/most of us here did the MacBook Pro EFI Update 2.1 back on May 4, 2011? It would take the Boot ROM to MBP81.0047.B0E iMac's ALSO had an EFI (1.6) update on May 4, 2011 - Boot ROM version = IM121.0047.B0A - Coincidence, I think not...

lots of problems with my iMac after upgrade to Lion. After few days using Lion some application start freezing: Firefox, 1Password and etc. It was not possible to shut down computer, grey screen and closing animation in the middle. 20 minutes, 2 hours - nothing. Pushing ON/OFF button and shutting down by this way.

Did reinstall, all from the beginning. First Snow Leopard then upgrade to Lion. First 3 days everything is just perfect, after same issue.

My iMac is 3 year old. Never had any problem. After 3 year happiness I got problem after upgrading to Lion.
iona60  2011-08-10 13:25
Which memory configuration do you have on the video card? 1 or 2 GB?
I make videos and have found on many occasions, such as just now, I have lost hours of work. Knowing I now have to log off every time I have done working on the i-mac will help.
However, I can't see this as a bump in the road because Apple, who are now richer than the oil companies, has an obligation to deliver a product that is thoroughly tested under all duresses. This is a monumental error by Apple who seriously need to find a solution or offer their suffering customers some for of apology. Tomorrow they will be informed of my thoughts
Hayley  2011-08-15 17:21
I am also having the exact problems you mentioned above. I called Apple and they did a bunch of troubleshooting. I told them that about this thread and many others I read about it being a problem with Lion, but the reps stated that they had no information on this at all. ?

Ironically enough, after I cleared my cache, watching video after a sleep mode no longer froze the computer. Guess we'll wait and see what Apple does.
Thanks for the great rundown, Kirk. You and I are definitely in the same boat, and our systems may have been on the same boat literally (my 21.5" iMac was also purchased in June '11).

Believe it or not, I think you can actually sometimes catch the problem before it crashes your system. I tried opening a Quicktime at one point and had that shudder-inducing green window you screencapped. Somehow, and I wish I knew for sure how, I was able to close the window without the system crashing--it might have had to do with the file not trying to actually play the movie yet, but I definitely saw that green first frame and was able to close it before it brought the whole system to a halt. It doesn't work every time, much to my chagrin, but it definitely did once.

Here's hoping the 10.7.2 update really does fix the bug...considering I'm in the middle of capturing DVD's and building a personal video server, problems playing video aren't very high on my list of good things.
Stephen Finlay  2011-08-17 10:06
So far I have been unable to reproduce the video freeze under the 10.7.1 update.
i am soo thankful that i ran across this article. THIS is exactly what has been happening to my brand new iMac and get this I'm on my 2nd brand new iMac. we dealt with the freezing problem for a month and then by our 2nd visit to the genius bar demanded a new computer thinking it was a "lemon" since they couldn't pin point the problem. after having our 2nd brand new iMac for just 2 days it TOO started freezing and i am beside myself with frustration.
colleen  2011-09-10 16:10
This is exactly my problem, thank you for sharing.
Antonio Rodriguez  2011-09-21 22:23
Any updates on this issue? As video producer for a journalism website this has significantly affected my work flow. Thanks for the help.
Adam Engst  An apple icon for a TidBITS Staffer 2011-09-22 00:53
As noted in the comments (and as we've covered in other articles), 10.7.1 seemed to resolve the problem for most people, and there was also an iMac Graphics Firmware Update that might help too. I'm not hearing complaints any more.
David M  2011-12-12 16:10
I am coming in late on this thread as I have been posting previously on the Apple Discussions Forum.
It is not only new iMacs that are affected as my mid 2008 20" has the same problem. Here are some of the facts that I have established:
Up to OSX 10.6.2 everything was fine; problems started with 10.6.3. I did updates to 10.6.7, hoping each time that the freezing would stop, but in the end I had to go back to 10.6.2 to get stability.
The freezing and spontaneous shutdowns are quite random and independent of application or system temperature.
I frequently run the iMac under Windows XP (using Boot Camp) with heavy workloads without a problem. The logic here is that in this environment the hardware and systems management work OK.
It was with some trepidation that seven weeks ago I did the upgrade to Lion, but, surprisingly, there was not a problem until a couple of days ago when I had a spontaneous shutdown, and yesterday there was another shutdown and a freeze. The issue is still there.