I also see an error in the nmbd.log (/var/log/samba) showing an error finding the master browser at the old IP address.
The wins.dat file contains the old IP address as the master browser and needs to be purged.
Stop the SAMBA nmbd & smbd services. Either using the command line or with web enabled swat http://server:901.
Change directory to /opt/K/SCO/samba/3.0.20Ad/var/lib/samba (or to the correct version in this case it is 3.0.2)
Redirect null into the wins.dat file (from command line enter: > wins.dat)
Restart the SAMBA server or reboot.