Thats what we are here for! Its probably a bit late now.. but here is a utility that can disable USB for you automatically http://www.intelliadmin.com/DisableUSB.exe
Right Click... Properties... Click the Desktop Tab... Click the Customize Desktop button on the bottom, and make sure that the My Computer has a tick in the box. Click OK, then click OK once more, there you go
If its a bad PSU, it wouldn't even power on. My guess is that the mainboard has blowed its stack due to a power spike most likely. Investing in a surge board is great!