USB devices may stop functioning on a Windows Server 2008 or Windows Server Vista SP1-based computer
On a Windows Server 2008 or Windows Vista SP1-based computer, all USB devices may stop functioning. This problem occurs after a surprise removal of any of the system’s USB host controllers. The USB devices function again only after the computer is restarted.
For more information on this issue, including potential causes, workarounds, and resolutions, see: Microsoft KB Article KB968551.