I presume you are using XP?
Are you plugging into the main USB connections on motherboard near mouse port?
Disconnect ALL USB devices. Go into Device Manager, select "show hidden devices" on View tab. ..
Expand tree and under USB Controllers, uninstall ALL entries there .. also uninstall entries under HumanID devices, and any USB entries under Mouse and Keyboard.
Shutdown PC and reboot. Windows should reinstall all device drivers for the USB entries.
If it does not .. you should look at the properties of the entries with any Q mark in yellow or suspect a hardware failure of some kind.
This could be onboard USB board or sockets on a plugged in USB card.