I would check out the /etc/hosts file. The RC file is calling the hosts file when creating the interface. To check and see if you have a miss confiugred host file try and replace the 'hostname' with the actual IP(will change it back later). If it sticks across a reboot then you have something wrong with the hosts file.
Current:
ifconfig nas `hostname`-nas mediatype auto netmask 255.255.255.0 partner nas
Try testing:
ifconfig nas XXX.XXX.XXX.XXX-nas mediatype auto netmask 255.255.255.0 partner nas