I have an AMD athalon 500 MHZ, 128 meg ram, and an nVidia 16 mb video card. Every once in a while it resets for no reason. It gives no error messages just starts rebooting. I've heard that this may be a fan, or overheating problem, but I've checked that and the fan is running, and I installed an extra case fan and it still is doing it. It seams to do it more often when I am doing things with more graphics, like games or scanning. But it does it with no pattern of what programs I am running. Any sugestions.