Those fans push air over heatsinks (also known as lint collectors) and you could have a cooling issue or just a tired power supply.
Tell a little about your maintenance routine and consider that you may have to repair the machine.
-> http://reviews.cnet.com/5208-6142-0.html?forumID=5&threadID=123670&messageID=1401360 is a good story about someone that thought they had no pests, but in the end found their fix.
I was running a program that i've ran on my computer probably about a 1K times (literally) about a month ago when the computer just restarted by itself. It then proceeded to stay stuck on the Windows loading screen. It entered the BIOS ok, but never loaded Windows. I just disconnected the power, turned it on again, and it loaded normally. Since then, my computer had either restarted by itself or stays stuck on the loading screen. The times when it does restart and load normally a dialog box comes up and says "Windows had recovered from a serious error."
I know it's not restarting because of malware, because i've fixed friend's computers full of spyware with that as a symptom. I'm running a 2001 Compaq computer, Windows XP SP2, 1.8GHz, 512 RAM, and recently installed an ATI Radeon 9600 video card.
Any help with this would be greatly appreciated. Thanks!