Some more information about the AD would be nice:
1) Is this a new AD?
2) Is this the only Domain Controller? / How many do you have?
3) Was the server upgraded to Windows 2003 or build from scratch?
4) Is the DNS zone Active Directory Integrated?
These questions aside… I would check the DNS console and see what is actually in the zone that represents your Active Directory Domain. If there is nothing in there, I would make sure that the Domain Controller’s IP Configuration is set appropriate to point to itself. If the DNS was installed as part of running DCPROMO, I would check to make sure there is no root zone, a zone distriquished by a single “.”. Also, make sure the root hints appear correct for the server.
Then run NetDIAG and DCDIAG from the Support Tools. These will help further diagnose the problem.
If this is the one and only DC and it was newly created I would check that you have a SYSVOL share. My guess is that you do not and thus do not have a working Domain as yet. If nothing seems to be working correctly and you have additional domain controllers that ARE working, I would DCPROMO the system, uninstall DNS, reinstall DNS and run DCPROMO to make it a domain again.
If this is the ONLY domain controller, I would find another Windows 2003 server. Setup DNS on that server and create a primary DNS zone for your Active Directory. POint the troubled Domain controller to this DNS server. Make sure the system correctly registers the SRV records – the funny looking was like _ldap._tcp… Then uninstall DNS on the troubled server. Reinstall DNS then create the AD Integrated zone for the domain. Point the domain controller back to itself and run IPCONFIG /REGISTERDNS. Make sure the SRV records are properly populated. Then, run DCDIAG and NETDIAG to see that they look healthier.