win98 not working with dhcp

in our WAN network, we have win95,98,2000 and xp machines.
all on dhcp and were working well. changed name of domain
by adding .local to domain name and the win 98 machines
will now not get a valid ip address from dhcp. the
win95, 2000 and xp machines still work fine. all we had
to do was change the name of the domain. we have had to
go back to static ip's for the 98 machines in order for
them to access the network. what's the problem? thanks
for any helpful response.