>> Unfortunately, CLOSE ALL is spread throughout the code of
>> all the programs so using a low level file open/create to
>> make a file that only exists during execution of the program
>> won't work. This is the method I've used in the past.
>
>How about creating a permanent DBF? Every time a user logged
>in, a record is inserted into it; logout, removed from it.
>A look into the table will know who is/are using a program,
>what program, when... Then you can control access.

This approach only works if the app NEVER dies or is terminated abnormally. The client's server is EXTREMELY unstable. Users are kicked out several times a week which would leave the records saying that users are still logged. Therefore this would not work in this situation.