Möglicherweise dieses Problem ?
--> http://www.intel.com/support/motherboards/desktop/sb/CS-026509.htm
Desktop Boards
USB Devices Disabled in Windows*
Symptom(s):
USB devices such as web cams and mice may stop working over time. The USB ports will appear as disabled in Windows* and recovery can only be done by shutting down the system, removing the power from the AC outlet, plugging it back in and restarting the system.
Cause:
This problem is typically due to improper grounding and integration of the desktop board. See below for an example of back panel connectors not properly touching the metal I/O shield (backplate).
Solution:
To resolve this issue, try these recommendations:
Implement proper grounding during integration and installation of the desktop board inside the chassis.
Ensure that the supplied I/O shield (backplate) is installed properly and that the metal connectors are touching the back panel connectors such as the LAN, keyboard, and mouse ports.
If a front panel USB connector is being used, ensure that the front panel is properly grounded to the metal part of the chassis.
