Help with computer crashing

[Exterous]

Two days ago everything was working fine. I didn't use my computer last night but tonight when I went to play Left 4 Dead or COD World At War my computer would crash about 5 min into the game. I have had no other instances of crashing outside of games.

Here's what I did:
Rolled back ATI drivers
Updated ATI drivers
Uninstalled the 1 windows update since the 26th
Restored the system to the 25th
Removed video card, cleaned with compressed air and re-seated
Cleaned out the rest of the case
Checked system, cpu and video card temps. Nothing out of the ordinary at time of crash

None of that seems to have helped. Any other ideas?

Also - of note I have noticed that my screen will sometimes leave....for lack of a better word....fragments of windows I have minimized/closed behind. They go away once i open another window over top of them

System specs:
Vista 64bit
6GB ram
E6400 (not oc'd)
ATI 2900XT

Thanks guys!

 

[Exterous]

Opps, just noticed there is now a 'Computer Help' section of the forums. Feel free to move

 

[Exterous]

So i noticed that ATI Catalyst control center was not opening so I reinstalled that from AMDs website. Loaded up L4D and sure enough, it crashed.

But here is a new twist. When restarting, it will show the MB splash screen and then the POST screen, but then my monitors lose signal. Windows continues to boot successfully ( I can hear the windows sound when it finishes loading)

To double check, I tried starting in safe mode, but after the list of files being loaded scroll by I lose signal again

Is it a hardware issue even though the splash screen and post screen show?