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
sfc /scannow
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