Domain Controller error on Windows Server 2003

I have parallels installed on a Mac and have window xp install on the computer as well. I configured the Mac to connect to the network domain and received the domain controller error that it could not connect. The only way I am able to get it to work is to disconnect the ethernet connection under the network adapter pulldown menu and then reconnect. I am trying to join a Windows Server 2003 domain. Since the user need to access the pc remotely this setup can work this way until I figure out the problem. Any help would be appreciated.

Phil Z