How to Disable Access to your Pendrive in your PC

To disable the access to USB port, in windows Vista / XP follow the steps below

1. Goto Start and click on Run and type Regedit, and then click OK.
2. In the registry menu Locate and then click the following registry key:

3. HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\UsbStor

4. In the right hand pane double-click Start as shown in the image below.
5. In the Value data box, type 4 and then click OK.
6. Quit Registry Editor and refresh your desktop.

More at Microsoft Website Here