I have a SBS 2003 server, which other than this issue has been fine. When creating a new, user the process completes fine but the user doesnt get a mailbox in the mailbox store. Normally you may have to go to OWA and login to initialize the box if the user doesnt have Outlook but now all email services for that user do not work. In the AD user settings, the Exchange tabs have all the correct information and features listed. Other than re applying service packs, I cant think of any other solutions.