pc freezing

[mrz0gz]

I've had my custom built rig for about 3 years now and never had any problems... just recently I've been playing my PC games AGAIN and I've noticed my game locks up and makes loud nosies, the lock up very in games apb last about 20 min, while left 4 dead last 5 min max. I've been looking into a lot of forums but haven't been about to find the solution. Any advice/solutions would be greatly appreciated. I have a picture down below to show what happens when computer freezes.

soultions I've tried:
* registry cleaner
*defragmentation
* cleaned out my entire system with duster( also changed thermal compound on CPU)
*installed latest drivers for video card ( also tried the omega drivers)
* tested my GPU with OCCT, tested RAM with mem test, checked my temps on CPU, and GPU and PSU

SPECS
*windows vista ultimate 64 bit
*intel core 2 duo 3ghz
*4 gig of RAM
* Nvidia geforce GTX 280

http://i810.photobucket.com/albums/z...1162/photo.jpg <--- after playing l4d 3 mins