I came across an odd bug a couple weeks ago with MacOS X 10.6.6 and the “Desktop & Screen Saver” System Preference pane. Seemingly out of the blue, when I attempted to modify my screensaver, it would just hang indefinitely and when attempting to click it again it would (usually) crash with EXC_BAD_ACCESS (SIGSEGV) errors. At least anecdotally I seemed to be experiencing crashes of other applications, incl. Steam and Safari (Flash plugins) as well. I could be completely out to lunch, but it seemed as though this issue just manifested for the first time in January after working fine for months. After running through a long list of diagnostics and fairly extensively researching this issue with Google and on Apple’s support forums, I finally called Apple Care to see what they thought.

To make a long story short, after visiting an Apple Store to demonstrate my mystery bug, we discovered that what apparently happened was that I reinstalled the operating system using the retail MacOS X 10.6.0 DVDs rather than the MacOS X 10.6.3 DVD that shipped with my Mac Pro when I purchased it last summer. As best we could tell, even though the installer appeared to work without issues, I ended up with the incorrect drivers due to the fact that the 2010 Mac Pro (5,1) didn’t exist when Snow Leopard originally shipped.

I’m posting this primarily because there was nothing online related to this issue and hopefully if somebody else comes across this problem they can save themselves some effort and headache. This problem is particularly nefarious because you can still apply the 10.6.6 update without any evidence that there are issues but you will still have the bug despite being completely up-to-date.

First thing tomorrow, I’ll be calling Apple to order replacement reinstallation media.