Hi raleigh,
Sorry for I ask again.
Your website is
www.mydomain.com and can be found by
http://www.mydomain.com and/or by
http://mydomain.com. I'm I right?
If you look at Domain settings what do you see?
If is like you say, you should see:
Server Role: Domain controller
Realm: mydomain.com
NetBIOS domain name: mydomain
NetBIOS computer name: www
But I'm not so sure.
Maybe it's only a matter of DNS.
What do you see at Network -> DNS -> Search Domain?
What dou you see at DNS -> Forwarders - Forwarder and at DNS -> Domains - Domain?
EDIT:
I think that you have nothing at Forwarders and your local users search only by Search domain that is local domain.
At Search domain you should have what is at Realm and at Forwarders, an external DNS.