MacBook Pro 3,1 (2007), running 10.6.8, sudden logout, window_server crash I have a 2007 MacBook Pro 3,1. The logic board, graphics card, and hard disk were replaced in October 2009. 

Sometime in the last few months the machine began to 'spontaneously logout' - I'll be using the machine normally, there's an unexpected pause - then blue screen/login dialog. The console logs show that the window_server has crashed. I can't find a way to reliably reproduce this, other than to simply wait - it now happens daily. The problem occurs in response to some interface event, typing or moving the mouse - I (still) use Spaces, and the most common trigger seems to be switching between spaces. 

I've spent a lot of time reading various threads describing similar problems, often associated with the nVidia graphics card, but haven't yet found a solution (or even been able to localize the problem). I've tried many possible fixes: backed out all 3rd party kernel extensions, minimized the set of active applications, purchased/installed new memory, run the apple diagnostics, tested/verified the disk appears ok, removed all apps which were starting on login, disabled the screensaver, the hard disk sudden motion sensor, the battery has been replaced, I'm not actively running (but have loaded - Office 2008) some Rosetta apps... none of this has made a difference.

Any advice is appreciated.
Although I can't be 100% certain I've fixed the problem, it's now been 3 weeks w/o a reboot - in my case, I believe the fix was turning OFF the 3D graphics acceleration option in VMWare (I run VMWare Fusion, w Win XP vms, constantly).