What do you mean "the network is telling all the other machines it is 192.168.1.90"? Do you have a bad DNS entry for it?
The log messages look like your MS machine (2k or XP) is trying to do Dynamic Updates to DNS. You can turn that off on the properties for the network card, since I don't belive the DNS Server that comes with E-Smith supports Dynamic Updates (I could be wrong).
If you are running Exchange 2000 it does require an Active Directory integrated DNS server to function properly. If you don't provide it one on install it will try to configure itself as a DNS server, so that could be part of your problem.