Second, did you ever have an overvoltage error on the USB ports? Have you tried a BIOS update? Since you said it happens with several USB devices, which have you tried? Try different things, not just USB drives, maybe a printer also if you can.
This looks like a motherboard issue at first sniff.
It's a teacher's laptop at one of the schools i work at. She gets this with any device she plugs in that isn't already installed. I am not back at that school until friday so will ask her then about the overvoltage and i will look for a BIOS update.