Mac clients unable to log in with DC at 2003 SP1 and Excha..

Greetings,

We have an issue that has arisen with our Mac users after we upgraded to
Windows 2003 SP1. We are running exchange 5.5 on a windows 200 server and
all has been well until the DC's were upgraded to Server 2003 SP1. Now all
Mac clients logging into outlook 8.1 (Most are running OS 10 in classic
mode) get an error stating "The logon credentials were incorrect. Make sure
your username and password are correct and try again." The problem is that
their username and password are correct, and regardless of what user tries
it they get the same error. Eventually the user's AD account gets locked
out for failed attempts. So its getting to AD just not authenticating
correctly. If anyone can help me I would appreciate it. Thanks again.

+++++++
Correction!! We are running Outlook 2001. I apologize!
+++++++
"Brandon" <brandons780 RemoveThis @comcast.net> wrote in message
news:e1BvIMEyFHA.3152@TK2MSFTNGP10.phx.gbl...
> Greetings,
>
> We have an issue that has arisen with our Mac users after we upgraded to
> Windows 2003 SP1. We are running exchange 5.5 on a windows 200 server and
> all has been well until the DC's were upgraded to Server 2003 SP1. Now
> all Mac clients logging into outlook 8.1 (Most are running OS 10 in
> classic mode) get an error stating "The logon credentials were incorrect.
> Make sure your username and password are correct and try again." The
> problem is that their username and password are correct, and regardless of
> what user tries it they get the same error. Eventually the user's AD
> account gets locked out for failed attempts. So its getting to AD just
> not authenticating correctly. If anyone can help me I would appreciate
> it. Thanks again.
>