samba - Mar 2005 - Can't browse the network

Hi,

I have a Mandrake 10.1 with Samba 3.0.10 and clients with windows 98 & XP.
I can't browse the network from clients computers.
Logfile:

Mar  8 09:21:27 www smbd[13792]: [2005/03/08 09:21:27, 0]
smbd/service.c:make_connection_snum(570)
Mar  8 09:21:27 www smbd[13792]:   Can't become connected user

My smb.conf:
#======================= Global Settings 
====================================[global]
    log file = /var/log/samba/log.%m
    smb passwd file = /etc/samba/smbpasswd
    load printers = yes
    socket options = TCP_NODELAY SO_RCVBUF=8192 SO_SNDBUF=8192
    force group = estmas
    map to guest = bad user
    encrypt passwords = yes
    printer admin = @adm
    allow hosts = 192.168.0.
    dns proxy = no
    netbios name = fileserver
    server string = Samba Server %v
    printing = cups
    workgroup = ESTMA
    os level = 255
    local master = yes
    preferred master = yes
    interfaces = 192.168.0.0/24
    bind interfaces only = yes
    valid users = @estmas
    printcap name = cups
    create mode = 775
    security = user
    max log size = 50
    directory mode = 775

Anyone else know anything about this ?
Please, help!

Kindest regards
Oleg Minakov.