Outlook XP will not authenticate to Exchange 2003 keeps asking for user password / nt credentials

I have a Windows 2003 Server SP1 with current updates, Exchange 2003 with all SP and udates.  There was a problem with the Group Policy infrastructure in the DC and group policies wre not being applied.  The problem was fixed and the Default Domain Policy which comes pre-configured with password to expire in 42 days was accidentally applied.

When all the users password expired and the users proceeded to change it all Outlook XP clients lost the ability to authenticate to the Exchange 2003 server.  this occurs in Windows 2000 Pro and Windows XP stations.

I set up two new computers with Office XP only and downloaded all relevant service packs.  So I now have two brand new Windows 2K and XP Installations with Office XP all updates applied and no additional software.  The problem persists, I can't authenticate using Office XP, with Office 2003 I hav no problems.

Roaming profiles are not being used and the user profiles in these 2 workstations are new as well.

I have tried all the solutions found in Microsoft regarding RPC connectivity, the Registry entries, the RPC binding order and I also used the RING tool to establish RPC connections with the Exchange server.  The rping connections were sucsessful and the RPC Registry entries are correct.

Thank you