[Samba] Empty Network Neighborhood"

[Peter Volkov Alexandrovich]

Hello.

My problem is not samba realted, but I might hope that it can help me to solve 
it.

Our network is about 200 users. Some of them are using windows. But today 
Network Neighborhood on all computers became empty. I've tried smbtree and 
its listing is empty too. If I enable -d10 I can see in the last string:
"Unable to find master browser by broadcast"

The only idea I have, some one have configured samba server, and so it may 
become master browser and then closed by bad firewall rules. But how can I 
inspect this?

Thank you in advance,
___________
Peter.

P.S. Our network enviroment, do not allow me to see what is running on users 
computers. They can do with their computers, whatever they want.