I spent about 11 hours today on one single problem with a family computer where the USB ports had suddenly ceased to function. No input from keyboard and mouse, which were wireless, and printer suddenly telling me it was "offline". Well, anyway, I finally determined that the USB ports were at fault, even though they appeared to be OK. I decided to put an add-on PCI card into one of the slots, let the drivers load, and would you know it… ALL ports on the computer except one started working just fine. Don't know… can't explain it.