Applications :: Apple Mail Cannot Sync With The Exchange 2007 Server?

So I'm rolling out 10.6 on some Mac Pros in our office. So far it's gone fairly smoothly (aside from the fact that Xerox has decided to not bother make drivers for 10.6). We're switching over to Apple's Mail/iCal/Contacts instead of the buggy Entourage. Of the 4 users, 3 of them are working fine. Sometimes their AD session goes buggy and they can't access shared folders on our server via smb, but a restart fixes it. I have one user who comes in every morning though, and her Apple Mail app can not sync with the Exchange 2007 server. It prompts her for her password and won't accept it. She can access shared folders though via smb and they open up right away, meaning it's recognizing her domain and user/pass with out her entering it manually.