first time it happened I was playing Prototype, my speakers made a weird click sound and the screen flashed. I could still play the game but without sound.
then it happened playing Combat Arms and it crashed to blue screen.
I took out my graphics card and used my onboard one.
I played Lunia and it did the same, but it crashed to desktop and not blue screen.
this is what it looked like when it was at desktop.
notice the colors at the top of windows live.
here are my specs.
vista x64 bit
AMD Athlon Processor 64 X2 Dual Core Processor 6400+ (2 CPUs) ~3.2GHz
4 GB Ram
Direct X 10.
NVIDIA GeForce 8500 GT
600 Watt Power Supply