Open Transport vs. QuarkXPress -- I've heard reports of two conflicts between Open Transport 1.0 (shipped only on the Power Mac 9500s) and QuarkXPress. If you have an XTension installed that receives the XT_NETRECEIVE opcode, QuarkXPress will hang on launch. I doubt there's any easy way to determine if you have such an XTension loaded other than by empirical testing. Apparently, Open Transport 1.0.1 fixes the problem. Even with Open Transport 1.0.1, if you have either the printer port or the modem port chosen as your network connection in the AppleTalk control panel, QuarkXPress will hang on launch if any XTensions that use network serial copy protection are installed. [ACE]
Sleep (and Lock) Your Screen
When you are walking away from your computer, it's fairly common practice to start your screen saver and lock your screen. But did you know that there is a built-in keyboard shortcut in Mac OS X to sleep the screen?
Press Control-Shift-Eject and your monitor sleeps without engaging the screen saver.