In the downloads look for clsevent.prg and use the following code in the main program to call. The late Ed Rauh wrote it so he gets all the credit. It works great for me. If you can't find it email me and I will email it to you.

Gaylen

SET PROCEDURE TO CLSEVENT ADDITIVE
PRIVATE oAppEvent
oAppEvent = CREATEOBJ('cusEvent')
IF TYPE('oAppEvent') # 'O'
   *  either the Event already exists, or it is not creatable.  IAC, don't run the app
   QUIT
ENDIF

>I want to run my Application EXE File Only one time, if the user try to run the application again on the same machine I want the application not to run again, so I need only one instance of my EXE file, any help on that.
>I am using VFP 6.0