What's the exact error number returned from the driver (it'll usually be in the message).
Presumably no tools that use ODBC to connect work from that client - if you haven't tried look at CUDLI or Distribution List Builder just to be sure. I've had a few of these reported and most of them that we managed to track down had to do with security apps blocking the connection from the client side and/or blocking the app (i.e. Vista when you're running as something less than Administrator). Best I can suggest if you've ruled that out for yourself is to try another desktop - this is straight up, no fancy-stuff ODBC connections - nothing more. No HTTP, no SCP no file transfers no nuthin' - just ODBC. It's about as straight forward as you can get for remote DB access.
