OK a very odd set up here.
The best course of action is to assign static IP address to your server NIC, then you should be able to Team/Bind more together and use some fault tolerance.
Windows 2000 IP changing
Teaming
Each NIC then appears to the rest of the network as ONE unit
IP Address: 192.168.100.x
Subnet 255.255.255.0
Gateway 192.168.100.1
WHat box is doing the DHCP function ?
Have you tried setting the scope up for a larger range, e.g. 192.168.100.10 to 192.168.100.100 ?
Do you have any static addresses already assigned ?
Are clients setup for Dynamic DHCP ?
Hope this helps