1) Click Start, and then click Run.
2) In the Open box, type regedit, and then click OK.
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\UsbStor
In the right pane, double-click Start.
In the Value data box, type 4 (to disable), click Hexadecimal (if it is not already selected), and then click OK.
4) Quit Registry Editor.
Note: In the Value data box, type 3 (to enable), click Hexadecimal (if it is not already selected), and then click OK.