No Premission To Log On Exchange

We recently relocate a user to another location of our office, we are using Windows NT Domain and we rename his ID prefix but without making any changes to his profile. He also user Outlook 2000 to logon to ou Exchange 2000 Server which is fine before relocate. Then, afer we have created his profile on the new Windows XP, we checked the name and teh correct full name can be returned by the server. It seems everything is fine but when he start the outlook, he got the “Unable to Open e-mail folder, You have no Permission to Log On”. Why is that and how can I fix it? Thanks!