Did you try disconnecting the case USB connections? It could be that one of them is doing something funky like shorting out....
Other than that, if you've already done a full OS re-install then it's definately something hardware related, and if nothing is connected to a USB port then it's either your motherboard, the connections to the USB headers, or possibly a couple of the pins on the motherboard USB headers shorted together.
__________________ EVGA X58 3X SLI / i7 980X / 3X 4G Mushkin Blackline Frostbite / XFX Pro 1000W / EVGA GTX 680 SC+ 2GB / Corsair F120 / WD 6401AALS / TT Lvl 10 GT Swiftech MCP655 WC Pump / EK XT 240 Rad / 2X Scythe Ultra Kaze / EK Supreme HF / Primochill Myriad Dual Bay Res / Dell UltraSharp U2412M Sabertooth 990FX / PhII X4 965 / 2X4G Corsair XMS3 / EVGA GTX580 + EK Block / Corsair 120G Force GT Corsair TX750 / XSPC EX240 / Swiftech MCP655-B / XSPC Dual Bay Res / ? CPU block / Bitfenix Ghost / Samsung 931BF |