I think the only viable solution is to create a personal user share and limit that share to one concurrent connection. If the user logs in the first time he can connect to his personal share successfully. However, if he tries ot log in to another computer he will exceed the maximum allowed number of connections to his personal share and the resulting ero message for the USE command will indicate that he's already connected once. Thus, the script can then for the logoff and promt a note about it. See Concurrent logins
_________________________
There are two types of vessels, submarines and targets.
