We have about 10 computers out of 600, where the User GPO setting to lock computers is not functioning properly. We used IDLE TImer to watch the computers activity, There was no activity and after 30 minutes the screen goes black. However, the desktop will not lock until you move the Mouse. We also updated mouse drivers. We logged in as a new user and the same problem occurred. In checking the register the settings are correct. Where do we go from here?