samba - Jun 2012 - NMBD stops working with "started asyncdns process" message

Hi there all!
I tried to find a resolution for my issue but I was unfortuned.
After few days of working samba PDC disappeared from the browser list 
and stopped to receive users. The last message in the log.nmbd is:

[2012/06/27 15:37:08,  0] nmbd/asyncdns.c:155(start_async_dns)
   started asyncdns process 23789

May anyone explain me that if there was the same problem?

-- 
Faithfully, Andrey Grebennikov