[Samba] Roaming profile : taking forever to login /log off

[FM]

Hello everybody,

We are using SMB as PDC and roaming profile.
but login /log off are taking 15 min (200 MB) on our GB network.
when I use tcpdump to monitor SMB on the client and the server , I can
see that  the copy  hang during several minutes.
our stations :
win xp sp2 (webclient disabled)

our smb serveur : samba-3.0.9

here is my smb.conf :
# Global parameters
[global]
        workgroup = DOMAIN
        server string = DOMAIN PDC Server
        interfaces = IP
        passdb backend = ldapsam:ldap://ldap-master.lan.lexum.pri/
        passwd program = /usr/local/sbin/krb5_update_pwd.pl -u %u
        passwd chat = *Password:* %n\n *Again:* %n\n *Changed*
        username map = /etc/samba/smbusers
        unix password sync = Yes
        log level = 10
        log file = /var/log/samba/%m.log
        max log size = 50
        name resolve order = wins lmhosts bcast host dns
        time server = Yes
        socket options = TCP_NODELAY SO_RCVBUF=8192 SO_SNDBUF=8192
        printcap name = /etc/printcap
        add user script = /usr/local/sbin/smbldap-useradd -m "%u"
        delete user script = /usr/local/sbin/smbldap-userdel "%u"
        add group script = /usr/local/sbin/smbldap-groupadd -p "%g"
        add user to group script = /usr/local/sbin/smbldap-groupmod -m
"%u" "%g"
        delete user from group script = /usr/local/sbin/smbldap-groupmod
-x "%u"
        set primary group script = /usr/local/sbin/smbldap-usermod -g
"%g" "%u"
        add machine script = /usr/local/sbin/smbldap-useradd -t 5 -w "%u"
        logon path = \\%L\%U\windows
        logon drive = Z:
        logon home = \\%L\%U
        domain logons = Yes
        os level = 33
        preferred master = Yes
        domain master = Yes
        dns proxy = No
        wins support = Yes
        ldap admin dn = cn=samba,ou=LdapSystem,dc=lan,dc=lexum,dc=pri
        ldap group suffix = ou=Group
        ldap idmap suffix = ou=Idmap
        ldap machine suffix = ou=Computers
        ldap suffix = dc=lan,dc=lexum,dc=pri
        ldap ssl = no
        ldap user suffix = ou=Users
        hosts allow = 192.168.4., 127.0.0.1
        cups options = raw
        mangled names = No
[homes]
        comment = Home Directories
        read only = No
        browseable = No
        csc policy = disable

[netlogon]
        comment = Network Logon Service
        path = /etc/samba/netlogon
        guest ok = Yes
        share modes = No