THere are no scheduled tasks on the server at the times we receive the login failure. No SSIS packages, no SQL Agent jobs at these times either. I don't think there are any Web apps on this server either. This is quite the mystery. It certainly seems like a schedlied event, but I don't know where else to look. I'm not a server administrator but have asked our srever admins to check and they don't see anything.

Thanks for your help. If anything else occurs to you please share!