Do you mean you want to keep a user from starting another instance of the application on two different machines or simply prevent multiple instances of the app on a single machine? If the latter, I put some code up here in the download area, FirstInstance.prg, years ago that stops the user from running more than one instance of an application on the same machine. (It was written for NT and I haven't tested it lately.)

Gary

>Hi,
>
>I want to be able to lock a user out once they are already logged in to my application. I currently do this using a DBF file in which I lock a record (RLOCK()) when the user logs in. The RLOCK() automatically gets released when the user shuts down the app either by logging out of if there was a crash or the user terminated the app or switched off the PC.
>
>Is there a way to do this using an SQL Server database? I am trying to avoid having to create another shared folder to put just this one DBF in.
>
>Thanks,
>
>Frank