make w2k server a domain controller

Hi,
We have a w2k server which refuses to see itself as a domain controller. If I open any AD snap-in. I get an error message stating that no domain controller was found. This is also preventing users who log on from being validated.
If I search for a domaincontroller and enter the w2k server name it still fails to find itself.
Do I have to demote it to a member server then promote it??