Adobe has disclosed in a recent TechNote that Photoshop CS5 can crash when doing a variety of tasks if you have certain MultiMaster fonts installed/activated.  Unexpected quits can occur when clicking the mouse, using type, pressing tab, launching Photoshop, or just working on a file.

Adobe’s fix for these MultiMaster related crashes to either deselect “Font Preview Size” in Photoshop’s Preferences->Type, or remove the conflicting fonts.  They have posted a FontTest script here, that claims to scan for fonts that can cause these crashing issues:
Some people have found that giving a conflicting MultiMaster font wide open permissions will prevent it from crashing Photoshop CS5 (and old school trick Techcare has been using for years), and rumor is Adobe is working on a fix.

Apple revved their Mac Pros product line on August 9th.  Of note from a troubleshooting perspective, these new Mac Pros boot into 64-bit (just like Xserves).  This is the first desktop Mac Apple has released that by default boots into 64-bit mode, and therefore will not run 32-bit applications without restarting holding down the 3 and 2 keys.

Tip: To easily check if an Intel-based Mac is booted into 32-bit or 64-bit mode, click on the Software section in Apple System Profiler.  There you will see “64-bit Kernel and Extensions” followed by either Yes or No.