Service won't stay started!

I'm running ZFH 5.1.

The darn service that runs on the windows servers won't stay started.

It will start up fine, run for about 5 minutes and then stop.

In the event logs there are no entries to show errors or problems.

The servers are Windows 2003 or Windows 2000. I've tried it on both versions.

Any ideas?

Thanks,
Cheryl