O.K. - I've beaten my head against the wall and hope someone here can help. I have migrated from an NT domain to a 2003 one. I created an NT server, upgraded it, then did it again with another machine, and then did a clean install on each machine (so we kept all the domain settings for accounts, etc. but got clean installs). The old NT PDC, now a BDC remains on the network, and there is one NT server still there, which is just a server. The problem is that the NT server keeps being on and falling off the network. It will be reachable from other machines on the network, and then suddenly will stop, saying that no domain controller is available. Then it will just suddenly become available again. I need to have access to this machine because it has several very active SQL Server databases on it. I am constantly told that NT servers work with 2003 in interim mode, and our old BDC is not having major problems, but this one is. It has a static IP that is in the DNS. I can ping the DNS server (when it's on the network). Any ideas?

What do you mean "when the dns server is on the network"??? Your dns server should NEVER be off the network. I have to assume the DNS server is one of the 2003 DCs. You are in mixed mode so you have NT compatablity, right? Have you brought up a Wins server under 2003? My suggestion is bring up a Wins server. Have it pull from the NT Wins server which I am assuming is on the NT BDC. Be aware that the behaviour you describe is also the signs of a intermittent nic failure/switch port failure on the DNS server [on again off again] or the NT server. Hard to tell without conducting some tests.