I have a user that is not able to connect via Outlook (Outlook 2003) but OWA works great. This is not a new user and they have been on the Exchange 2007 server for quite a while. All of a sudden they called in because Outlook wouldn't connect anymore.
I tried everything and I can't come up with anything. I even tried moving their mailbox to a different OU and still nothing. I can also attach their mailbox to my Outlook via open another users mailbox.