samba - Dec 2013 - Server IP address change - still referencing old one

I?m running SerNet Samba 4.1.2 on Debian Wheezy.  I?ve changed the 
IP address of the server, and in log.nmbd I?m getting the following 
messages:


Become_domain_master_query_success:
There is already a domain master browser at <Old IP> for workgroup 
<DOMAIN> registered on subnet UNICAST_SUBNET.
Become_logon_server_success:
Samba is now a local logon server for workgroup <DOMAIN> on subnet 
<New IP>.
Samba is now a local master browser for workgroup <DOMAIN> on 
subnet <New IP>.

Domain_master_node_status_fail:
Doing a node status request to the domain master browser
For Workgroup <DOMAIN> at IP <Old IP> failed.
Cannot sync browser lists.


It appears to be a common problem, but I?ve tried the quoted 
solution of backing-up then deleting browse.dat and wins.dat, and 
also wins.tdb.  However, when I restart, the problem reappears, and 
wins.dat contains entries for the old IP address.

I think the neworking side of things is okay ? the hosts file and 
interface seem fine, and I can ping the server at the new address, 
but not the old one.