Is there a way to force an app to close from outside of that app? Something through the operating system? (Windows 98 or 2000)

Basically, when the backup runs, we need to force everything out of the app so the files are not open. We are aware of the possibility of data corruption and the suggestion of putting a timer in the app to shut itself down. What we want is a seperate program that will run on each workstation and shut the app down at a specific time. I found a mention of getting a hold on the app using the title, but from there, I don't know what to do with it. My search didn't turn up anything on actually killing the app.

Thanks,

Michelle