I have to disable USB drive storage on all my XP PCs since we do not want people using USB flash drives, drive key's or whatever you want to call them. I have made the change to the registry key: HKLM\System\CurrentControlSet\Services\USBSTOR\Start to a value of 4. The problem is that for whatever reason they randomly get set back to 3 and the USB drives will work. What else can I do to disable them for good? Can the registry key be deleted?