OWA 2003 broken after upgrading to Server 2003

Hello all,

I upgraded from Windows Server 2000 to Server 2003 last week and am having trouble with OWA. Before doing the server upgrade, I had Exchange Server 2003 installed on a Server 2000 box acting as a DC on our network (not the primary). I have the proper ports open on our firewall and OWA worked fine before the upgrad but after the upgrade to Server 2003, I cannot access OWA from internal or external computers. I simply get the message “Internet Explorer cannot display the webpage”.

Any ideas or suggestions? Help!