I have an NT 4.0 computer that I had to install Outlook XP on so it would be compatible with the users Compaq hand held. The computer is connected to a network and we are using MS Exchange Server. The problem is that when he tries to use his Out Of Office Assistant he gets the error message "The command is not available. See the program documentation about how to use this extension". I have gone into Tools - Options - Other - Advanced Options - Add In Manager and made sure that the Exchange Extension Commands box is checked. I would greatly appreciate any help to get this running.