First, see if there is an updated driver from your motherboard manufacturer
Do you have any USB add-in cards, or are all ports on the motherboard, or plugged directly to motherboard?
Is this a clean Win7 install, or an "upgrade"?
Try checking windows system files, run this
If sfc is clean, and there are no new USB drivers from MoBo manufac., then remove ALL USB devices to reinstall. In the Device Manager screen, rt-click on white space and Show Hidden Devices. Remove ANY hidden device, USB related or not. Then remove every controller listed under USB controllers. Then reboot