>>When trying to open the application, it will take some time to start, and then won't continue to open and then closes immediately in a few seconds. The other existing 5 workstation and the Server are all still working fine and still can be use and being used.

It's interesting if there's no error dialogs or logs, just a quiet shut down on more than one affected machine.

The most common cause for this used to be people testing in the IDE then building their exe without a READ EVENTS, but you already have the exe working properly so it's not that.

Is it possible that your error handling is shrouding something like missing dependencies on newer OS? E.g. Windows used to ship with standard VC++7 dlls needed by VFP or add-ons like Craig Boyd's encryption and archiving flls, but those dlls are no longer included in newer OS. The easiest way to avoid this sort of issue is to include all dependencies in your installation folder with your exe. If you confirm which flls and dlls are included in your distribution, an "aha!" moment may result.