Outlook 2k3 connection to Exchange 2003

[Scot]

I have just upgraded from Outlook XP to Outlook 2003 and
am suddenly unable to connect to my exchange server.

OutlookXP still works on other PC's.

When I go in to look at the mail account setup, I get the
error saying the echange server is unavailable. When I
change the exchange server name to the exchange IP (ie:
192.168.1.10), I get the error "The action could not be
completed. The Operation Failed". Ive checked the RPC
settings in the registry and all is fine. I try to type
in the domain name of the exchange server itself instead
of the ip and get the same error. On another occasion it
did take the IP but then automatically changed it to the
domain name and from that point on it would not even do a
Checkname on the username. This is simply driving me
nuts... HELP!!!!!!!!!!!!!!!!!!!!!