Just recently (actually today) my computer started shutting itself down. The first time it happened it ran for about 20 min then shut down and after that the most i could get it to run for was a few min., sometimes it wouldn't even finish booting. When I opened it up i noticed that the fan on my cpu heat sink wasn't working so i replaced the fan with another but I am still having th problem. I was just wondering if you have any advice on the matter. Personally i think it is either that I need a new heat sink or a new cpu.