Windows server 2003 - problem with AD and DNS

Ive just recently set up a test lab using VPC 2004 with one virtual machine running windows server 2003, one running windows xp pro and one running windows 2000.
Ive configured the server for ad, dns and dhcp.
When i try to configure any of the clients to join the domain i get the error

Code:

a domain controller for the domain could not be contacted

All services are up and running ok. Ive tried netdiag /fix but no good. Ive tried restarting the relevant services, no good.
Here are the errors recorded in event viewer for dns:

Error1:

Code:

The DNS server has encountered a critical error from the Active Directory. Check that the Active Directory is functioning properly. The extended error debug information (which may be empty) is "". The event data contains the error. For more information, see Help and Support Center at http://go.microsoft.com/fwlink/events.asp.

Error2:

Code:

The DNS server was unable to complete directory service enumeration of zone .. This DNS server is configured to use information obtained from Active Directory for this zone and is unable to load the zone without it. Check that the Active Directory is functioning properly and repeat enumeration of the zone. The extended error debug information (which may be empty) is "". The event data contains the error. For more information, see Help and Support Center at http://go.microsoft.com/fwlink/events.asp.

Error3:

Code:

The DNS server was unable to complete directory service enumeration of zone _msdcs.contoso.com. This DNS server is configured to use information obtained from Active Directory for this zone and is unable to load the zone without it. Check that the Active Directory is functioning properly and repeat enumeration of the zone. The extended error debug information (which may be empty) is "". The event data contains the error. For more information, see Help and Support Center at http://go.microsoft.com/fwlink/events.asp.

Error4:

Code:

The DNS server was unable to complete directory service enumeration of zone contoso.com. This DNS server is configured to use information obtained from Active Directory for this zone and is unable to load the zone without it. Check that the Active Directory is functioning properly and repeat enumeration of the zone. The extended error debug information (which may be empty) is "". The event data contains the error. For more information, see Help and Support Center at http://go.microsoft.com/fwlink/events.asp.

Can anyone shed any light on this for me as im what you might call "stuck".

Cheers all

Sheesh! This could be a whole mulititude of things.

What functionality level have you set the AD to?
Are the AD and DNS in the same domain
How have you set the virtual IP virtual 'NIC' to work
Do you get the errors on both the windows xp and 2000 machines when trying to connect

If it was not for the DNS errors I would say the is a problem establishing a secure channel to the domain controller, but the DNS could be a problem in conjunction with this or it could be THE problem....

Ive configured the nic manually for one of the clients and can ping the server and vice versa but i still cannot contact the domain to join it. Ive tried uninstalling dns and reinstalling. The only thing i can think of now is to demote/promote ad...what do you think?

Ive sorted it. Thanks for the help

...... How did you sort it??

Repaired the installation...it was a test environment.