I have the Antec SmartPower 2.0 500W. The fan in the back isn't spinning, and I don't know if it ever has. I just now noticed it. I started getting a few random restarts when I was messing with my network cables. It also gives random restarts(seldom) when I disable my firewall and go into My Network Places. The air that's coming out of the back of it feels pretty cool already though. Do I have a problem or can I do something to MAKE the fan spin?