[Samba] Windows 7 Pro/64 unable to contact domain controller

[Gary Dale]

I have a number of systems running Windows 7/pro 64bit connecting to a 
Debian/Wheezy Samba DC. After one was rebooted today, I was unable to 
log on with a domain account, with the usual message about being unable 
to connect to a domain controller.

After logging on with a local account, I tried rejoining the domain but 
was unable - again Windows complained that it can't contact the domain 
controller. Re-did the Window registry settings change to allow Win7 to 
connect to an NT-style domain but still no luck. Same when I turned off 
the firewall. Rebooted multiple times in the process.

I can connect to network shares on the Samba DC (3.6.6) and can connect 
with SWAT using the NetBIOS name but others can't connect to shares on 
this computer.

Any ideas?