You can place the "Call PromptBackup" in the Activate event but then you will need to create a boolean flag variable to only let it call it once or when the user minimizes or switches apps, when they come back it will active again.

Or you could use a timer that is set to enabled in the last line of the MDIForm_Load event and an interval of about 500 (30 seconds) to fire its Timer event procedure where you wil have the call to your "Call PromptBackup" call. Disable the timer as the first call as the next line of code should be the one calling the backup call..