No subject

     preferred master (G)

          This boolean parameter controls if nmbd is a  preferred
          master browser for its workgroup.

          If this is set to true, on startup, nmbd will force  an
          election,  and  it will have a slight advantage in win-
          ning the election.  It is recommended that this parame-
          ter  is used in conjunction with "domain master = yes",
          so that nmbd can guarantee becoming a domain master.
		  ...

If you don't want your Samba box to be a PDC, make sure you do not
set "domain logons" in smb.conf or use "domain logons = no"
in smb.conf file.

Akop