I am trying to use the Shell function to start a program from another program running as a service under Windows NT. The program running as a service parses a text file into smaller pieces that the application it calls with the Shell function processes. When the called application finishes it writes a text file to the drive that the other program (service)waits for. After writing the text file it then quits. When the original program sees the text file it then parses out another chunk of text and starts the other program again. My problem is that I am getting two instances of the called program running at the same time and they end up stomping over each other. How do I get the called program to exit before the original program calls it up again?