Chris,
Yes the objects, memvars, etc. are created within an application and cannot be accessed from another app.

You should use a table. Many people set login/logout flags. The problem with this is that if an app crashes or the user closes that app/pc then the user is still considered logged in eventhough he's not. You can use a trick to know quite reliably who's in an app:
During application startup, locate the user's own record within the users table and place an RLOCK() on this record. The lock is automatically released when you close the app (just make sure you don't close the table). In your "Who is logged in" program, you can simply check for records that are locked. This approach allows only 1 instance of your app by user. However, you could quite easily work around this limitation by adding another table where you keep track of each login/logout. You would then place the lock on the corresponding record of this table.

HTH

>What I mean is does an exe recreate objects each time it is run? Do you have to test if the object already exists each time it's run etc?
>
>As you can tell I am fairly new to all this!
>
>Thanks for any help you can offer...