I am having an issue with two computer's, the USB devices have stopped working.
I am able to work around the issue by booting to the Advanced Boot Options (F8) and selecting Disable Driver Signature Enforcement.
My other troubleshooting has included;
-updating the usb driver, there was no update from windows update
-deleting the usb device, rebooting to let it find the driver
-deleting the usb hub, rebooting to let it find the driver