I hate to admit here but I need help. My neighbors computer continues to shut down immediately upon turn on - maybe 3 seconds on turning it on and it shuts down. The PS fan starts up then the fan on the MB then it just goes down. Won't turn on again unless I unplug then plug back in. Definitely no virus because prior to continuously shut down it would stay on for about 15-20 minutes and I was able to do a full virus scan/spybot etc. Either way, when I looked inside CPU it was dirtier than anything I ever saw .. from the fans to the board itself. I cleaned that all out. I switched out PS thinking that was the problem, but it still shuts down. Switched out HD and even removed RAM. It was working fine until she had Windows XP put on it. (Which I really do not think that is the prob cause it was working fine for about 2-3 weeks after it was installed.) I had the PS hooked up to motherboard and no other hardware. Still shuts down. The capacitors look good upon initial visual inspection. Something tells me it was initially an overheating problem because of the grime/dirt on the fans and all inside the CPU. What else can I try to determine what the prob is here. Any help would be appreciated.