This trick works only on XP SP2 and you need to have administrator privileges.
- Open Registry Editor by Start > Run.
- Type in regedit.
- Browse to HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\
- Locate the sub-key StorageDevicePolicies. If it doesn’t exist then create it first. Create a new key under Control by right clicking on it so that you don’t create it elsewhere by mistake (as shown in the above screenshot).
- Right click in the blank area of the sub key you just created and create a new DWORD value by the name WriteProtect.
- Double-click it and set the value data as 1 (and 0 for disabling it).
- Click OK, close the Registry Editor and restart the PC.