[Samba] Clients disconnecting and msword problem.

[Kakà]

I've got a lot of this in my /var/log/messages :

nmbd/nmbd_browsesync.c:find_domain_master_name_query_fail(351)

the problem is that sometimes accessing to server from windows client 
the mapped drive disappear to return in a second or two. I've got 
another strange problem. Opening a word file on the server and trying to 
save, MSword tell me that "the disk is full" and can't save. I suppose 
mys erver sometimes disconnect from client ( all clients! ).For this 
problem take in count that only msword do that stuff. Excel for example 
works like a breeze.
 
This is my testparm output :

[global]
        workgroup = MARELLA
        netbios name = URANIO
        server string = Server
        log level = 3
        log file = /var/log/samba/%m.log
        max log size = 50
        socket options = TCP_NODELAY SO_RCVBUF=8192 SO_SNDBUF=8192
        os level = 60
        preferred master = Yes
        dns proxy = No
        wins support = Yes
        default service = dati
        inherit permissions = Yes
        inherit acls = Yes

[dati]
        comment = Dati su Server
        path = /home/samba/dati
        read only = No
        create mask = 0775
        directory mask = 0770
        guest ok = Yes


thanks if you can help me !