Problems with communicating to Active Directory

Hi, I have a windows 2000 server as the domain controller and all of the workstations are using Windows XP for the OS. The problem that I'm having is that I'm getting netlogon and w32time errors. Also when I try to add domain users to security settings, I cannot see the Active Directory, just the local computer. I can ping the server and I can access the shared drives that are located on that server.
The Computers are connected to the domain and I can logon with the domain user accounts. I have also tried using networking software that uses the Active Directory for information and according to the software Active Directory does not exist. Is there anyone that has had this kind of problem? Any Help is very much appreciated.