How can you disable it? How, through the Registry, of course! You'll need to be in the admin account, or yours must have admin privileges.
In regedit, navigate to HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Applets\Regedit and look for the value LastKey. Double-click it and clear the string. Then right-click the Regedit key (in the lefthand pane) and select Permissions. Set Permissions to Deny for any/all users/groups.