i think im having the same problem as stupidcomputer.. i recently installed a new PSU(Antec TruePower 650w) and a new video card(geforce 8600 gts). At first I still got to play HL2 in high settings before the problem started. I tried to play vegas but then it hanged up. I thought it was nothing so I just restarted my pc. But then it will either hang up after loading windows xp(before the welcome screen) and show a black screen or automatically restarts after loading win xp or show the blue screen error something after loading.. so i tried reformatting it thought it might solve the prob but after it reformats te drive for win xp.. it would hang up when its loading the set up files. is the problem my video card? is it the hard drive or mobo? will reseting CMOS help? i need a reply please.. i need to use my pc for a project. thanks in advance.