This started happening about 2weeks ago, The computer would loadup XP to the desktop and would be fine if i didnt do anything. But if i start a game or even start IE it would freeze for a second and then shut down, then i would have a problem trying to get it to load to the desktop, it would shut down while loading the OS or even while doing the quick memtest in the bios. The XP install was about 3years old so i decided to reformat. I still have the same problem. I've check all the temps and they are ok. cpu and gpu around 50C. Also if I let it sit for about 15min and then try running any program i won't have a problem, I've started to just leave to comp on for days, infear that it wont boot up again.