samba - May 2005 - AD DISCONNECTED.

Hi,
I'm working with samba 3.0.13-1, krb5...1.2.7-10 and following parameters
settings:

/etc/krb5.conf:
[logging]
 default = FILE:/var/log/krb5libs.log <FILE:/var/log/krb5libs.log> 
 kdc = FILE:/var/log/krb5kdc.log <FILE:/var/log/krb5kdc.log> 
 admin_server = FILE:/var/log/kadmind.log <FILE:/var/log/kadmind.log> 

[libdefaults]
 ticket_lifetime = 24000
 default_realm = SINTER.GKN.COM
 dns_lookup_realm = false
 dns_lookup_kdc = false

[realms]
 SINTER.GKN.COM = {
  kdc = MILAD01.SINTER.GKN.COM
 }

[domain_realm]
 .sinter.gkn.com = SINTER.GKN.COM
 sinter.gkn.com = SINTER.GKN.COM

[kdc]
 profile = /var/kerberos/krb5kdc/kdc.conf

[appdefaults]
 pam = {
   debug = false
   ticket_lifetime = 36000
   renew_lifetime = 36000
   forwardable = true
   krb4_convert = false
 }

/etc/samba/smb.conf:

[global]
        netbios name = MILLX03
        os level = 16
        wins server = xx.xx.xx.xx
        socket options = IPTOS_LOWDELAY TCP_NODELAY SO_KEEPALIVE
        workgroup = GKNSMI
        realm = SINTER.GKN.COM
        security = ADS
        password server = milad01.sinter.gkn.com
        encrypt passwords = yes
        allow trusted domains = Yes
        winbind use default domain = Yes
        winbind separator = /
        winbind enum users = Yes
        winbind enum groups = Yes
        idmap uid = 10000-40000
        idmap gid = 10000-40000
        template homedir = /data/user/%U
        template shell = /bin/false
        use sendfile = Yes
        printer admin = xxx
        admin users = xxx
        log file = /var/spool/samba/log.%m
        log level = 1 auth:10 sam:10
        max log size = 50
        printcap name = cups
        disable spoolss = No
        show add printer wizard = Yes
        printing = cups
        load printers = yes
        map acl inherit = yes

Sometimes early in the morning, I get in the office and my users are
disconnected by the server, I don't understand if the problem is on samba
side or W3k side.They are on the same LAN but W3k is connected to others AD
server in the world and it retrieve any policy information by them.
So I think that probably something happen ... Also because when I run wbinfo
--sequence it return me a list with previous NT domains and relative id and
AD "domain" DISCONNECT.
So , I would like to know why it happens and what can I do to reconnect it
again.
Thanks.
Marco.