I get this message with a few people when trying to set up Outlook with Exchange Server 2003:
Outlook cold not log on. check to make srue you re connected to the network and are using the proper server and mailbox name. The Microsoft Exchange Address Book was unable to log on to the Microsoft Exchange Server computer. Contact your system administrator if the problem persists.
These acccounts are able to access their e-mail from OWA. One of the things they have in common is they are using roaming profiles (I have many others running roaming profiles with no problems with Outlook). I have tried wiping out their profiles.
Some other background info on our system. Exchange 2003 running latest service packs on a W2K3 Server running latest service packs. Using AD for authentication (on another W2K3 server). Any help or guidance would be greatly appreciated!