HTTP 500 server error

Ok I think I have a hard one. One of our users was logging into a web site for a doctor. It worked fine in the morning but in the afternoon when she tryed it, it gave her that error message. We do use a fire wall but only give 404 error not allowed to access. I called the web site help desk and they can log on as the user with no problem. I looked up 500 error and it is a programing problem. Heres the answer I am looking for, how do I tell if its on my end or theirs? I have full Admin. rights and can setup logs to see whats going on. I tryed this from home through AOL and get “Microsoft OLE DB provider for ODBC Drivers error ‘80040e14’ [Microsoft][ODBC SQL Server Driver][SQL Server] Incorrect syntax near the keyboard ‘WHERE’.