Port 67 Problem

I run a Novell 4.11 network and Microsoft Network with 12 computers attached. I have a Hughes 2-way dish connected to my computer to connect to the Internet (my OS is Win2k). I use OrbitNet to share the Internet with the other users. I get an OrbitNet error that says it cannot bind the DHCP proxy to listen on IP address 90.0.0.1:67. I am not using a DHCP server and I do not have Internet sharing enabled. How can I determine what is useing port 67?