Win98 Logoff / Logon to Win2000 problem

Recently I installed a third server. Users with win98 who
click on Start - Logoff then change user name and try to
logon to the domain are getting a message about No Domain
Controller Available. If they shut down, then restart,
they can logon without problems.

This wasn't a problem for over a year with only 2
servers. I'm assuming something is not set correctly with
the new server, but I'm at a loss.

The machines are all running TCP/IP and logging into a
Windows 2000 domain. No other protocol is running. The
machines are all configured through DHCP on a server that
was in place before the new server was installed.

Thanks for your help. E-mail me if you need more details.