This article originally appeared in TidBITS on 2011-07-01 at 11:47 a.m.
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Mac OS X 10.6.8 Suffers Printing and Audio Problems

by Adam C. Engst

It almost seems that Apple is focusing so much attention on the upcoming release of Mac OS X Lion that testing of the last few Mac OS X 10.6 Snow Leopard releases hasn’t been up to the company’s usual quality. 10.6.7 suffered from font problems that had design professionals up in arms (see “Apple Releases Snow Leopard Font Update [1],” 26 April 2011), and now the just-released 10.6.8 is taking its share of lumps, with a variety of user-reported problems surrounding printing, audio, hyperactive Dock CPU usage, boot problems for PGP Desktop users, and more (see “Mac OS X 10.6.8 Update Preps for Lion [2],” 24 June 2011).

Printing Problems -- Most notable among the 10.6.8-related problems are those surrounding printing, with the print queue continually pausing and “backend” errors like the line below appearing in the system.log viewable in Console.

printer-state-message="/usr/libexec/ cups/backend/lpd failed"

Although many potential solutions were suggested in the Apple Discussions forum thread [3], ranging from repairing permissions to resetting the printing system (Control-click a printer in the Print & Fax preference pane and choose Reset Printing System), the most effective solution has been an AppleScript-based application called Repair10.6.8 [4]. It basically copies old versions of four Unix apps — dnssd, ipp, lpd, and socket — over the new versions installed by 10.6.8.

[image link] [5]

I haven’t experienced the problem, so I can’t comment personally on how well it works, but a number of people in the forum thread have had good luck with it.

Audio Problems -- There are a number [6] of complaints [7] in the Apple Discussions forum about audio problems of various sorts. While the details of the problems vary, the solution seems to be the same in all cases: replace the AppleHDA.kext kernel extension (version 2.0.5, if my Mac is any indication) installed by 10.6.8 with the version from 10.6.7 (version 1.9.9, even though it has the same creation date as the later version). Time Machine is the easiest way to get the AppleHDA.kext file back; it’s located in /System/Library/Extensions.

Parallels / Dock Incompatibility -- Many users of Parallels Desktop are reporting that after updating to Mac OS X 10.6.8, the Dock process starts taking 100 percent of the CPU, causing significant performance problems. The issue [8] is related to the option in Parallels Desktop that makes Windows applications appear in the Dock (specifically, it’s related to icons larger than 128 by 128 pixels). There’s an update to Parallels Desktop 6.0.12092 that solves the problem, or you can set each virtual machine in Parallels Desktop not to show Windows applications in the Dock.

Boot Problems with PGP Desktop -- Users of versions of PGP Desktop before 10.1.2 found that their Macs wouldn’t boot after installing 10.6.8, since Apple’s Software Update utility overwrites a critical boot file related to whole disk encryption during installation. PGP recommends upgrading [9] to at least version 10.1.2 before installing Mac OS X 10.6.8, but if that train has already left the station, you can follow a few quick steps [10] to replace the boot.efi file with the necessary pgpboot.efi file. If that doesn’t work, you’ll need to make a PGP Whole Disk Encryption Recovery CD [11] and use it to upgrade [12] or even decrypt your disk.

Other Problems -- Although I’ve seen other complaints, including slow boot times and strange color issues, most are merely anecdotal (which doesn’t mean they’re not real, just that they don’t seem to affect many people). Nevertheless, the standard fix for inexplicable problems that crop up after a Mac OS X upgrade is to download and install the combo updater.

The Mac OS X 10.6.8 Update Combo [13] contains all the changes since 10.6.0, and is a 1.09 GB download. You can install it directly over an unhappy installation of 10.6.8, or if all else fails, you can reinstall Snow Leopard from an appropriate Install DVD (the one that came with your Mac, if that’s newer than 10.6.0) and then use the combo updater to move up to 10.6.8.