Power supply went bad after 5 years.. I replaced it with a Cool Master 550 Watt. System booted up OK, but none of the USB ports work. The 4 rear USB ports are directly connected to the Intel motherboard. The front usb ports are cabled to a different area on the motherboard. After reading a few posts with the same issue, I'm thinking that the power supply connectors may be wired a bit differently, resulting in lack of power to the USB network. Keep in mind, Win XP boots fine...Win 7 on a separate HD boots fine. No way to control either one without a mouse or keyboard.