WINS loses information after restart

Hi all,

I have a MAC Pro 2008 running OS 10.8.5 and a couple of PCs on my wired LAN network.

My problem is that my MAC keeps losing the WINS information

in the Network->Advanced->WINS preferences every time I restart.

I want to be able to share a folder on my MAC with the PC's.

So, in System Preferences->Sharing->Options I have enabled the Share files and folders using AFP and the SUB (Windows) on my MAC account.

On the Network Preferences->Advanced->WINS I have the NetBIOS name set and the workgroup below that and LOCK to prevent changes.

All works great and I can 'see' the shared folders of my MAC from my Windows PC's and vice versa

BUT when I restart the MAC the WINS information is lost!

The username and workgroup is empty and it is UNLOCKED despite the fact I locked it before the restart.

The empty username and workgroup leads to have no access from my PC's.

If I re-set those it works again but why does it lose these info every time I restart?

Does anyone have any ideas?

Thanks!