I had the same problem and the following fixed the problem:
Since your USB keyboard & mouse doesn't work, you'll have to use one of the following to access the computer:
1. Use a PS/2 kbd & mouse.
2. Use a remote login session (assuming that you've enabled Remote Desktop previously).
Now remove & reinstall USB devices as follows:
1. Click Start, click Run, type sysdm.cpl in the Open box, and then click OK.
2. Click the Hardware tab.
3. Click the Device Manager button.
4. Expand Universal Serial Bus controllers.
5. Right-click every device under the Universal Serial Bus controllers node, and then click Uninstall to remove them one at a time.
6. Restart the computer, and then reinstall the USB controllers.
7. Plug in the removable USB storage device, and then test to make sure that the issue is resolved.