Well a couple of things to try (if not done already) would be:
a) Check out a dhcp server if you have that installed
b) Attempt to identify and dns server etc referencing the old ip.
c) rm_install_client and add_install_client ... though this is obviously disruptive.
Look down the add_install_client man page for clues ... http://docs.oracle.com/cd/E19082-01/819-2240/add-install-client-1m/index.html ( i haven't checked if this is the latest).