another issue with mounting the mounteddevices key... try this if you dont believe me...
if you (like me) have usb sticks/usb drives/firewire drives/network shares etc.. blocking the mounteddevices will make attaching any unit fail, so all in all messing with the registry i think is a bad idea as it could cause various system failures, anti blaxx got a lot of crap about causing system problems in the past, perhaps a lot of the blame was due to this 'side effect'... food for thought i think, if you are going to mess with your registry, make a backup first always, and if you are going to add in usb drives etc after playing the game or whatever, remember to unblock the keys