Tommy,
I use a similar method, but check every 30 seconds from a timer in the main window. Every 30 seconds it checks to see if there's a file called Shutdown.txt. In the text file, I have data on 4 lines. Line 1 = # minutes until it shuts down, line 2 indicates how many minutes it'll be down for and line 3 indicates the reason for the shutdown. Optionally, line 4 contains the station number of the *only* station allowed into the system once it has been disabled. When someone starts the system, if the file is present a polite "system is shut down for ..." message is put up. The system also sets a timer for 30 seconds before automatic shutdown that reminds them that the system is going down and gives one last chance to save any changes, before the whole thing just QUITS. This method has worked great for us over the years - worth a shot!

Happy Holidays!

Erik