The other day I was working on my computer, and I left for a few minutes. When I came back, I saw that my computer was in the process of logging me out, and then restarting. Obviously, I became very concerned, but everything appeared to be normal when Windows came back on. I then shut down the computer. About 20 minutes later, I came back and tried to turn my computer back on, but it wouldn't turn on. Aside from the mechanical clicking of the button, the computer sounded lifeless. I checked the power cord, and it seemed fine. To make sure, I unplugged it and could hear the computer "power down" as usual. I plugged it back in, hit the power button, but still nothing. I got really frustrated and started mashing the power button hard, and then it finally powered on!
Since then, I've shutdown maybe 3 times, and 2 of those times I had to mash on the power button to get it going again. Any ideas?
For reference, I'm running Windows XP on an Athlon 64 3400+ with 1GB of RAM. I built it myself, and I can't remember what PSU I have in there, but I remember making sure that it had ample watts. The only thing is that this computer runs pretty hot! I have an aluminum case with a few fans, but this thing heats up my bedroom in no time.