I have installed and set up several Samba networks in the past on Ubuntu servers and desktops.

ON a new Karmic desktop machine I am experiencing similar problems.

In the log.smbd I see lines such as:

[2009/12/17 18:28:11,  0] smbd/server.c:1068(main)
  smbd version 3.4.0 started.
  Copyright Andrew Tridgell and the Samba Team 1992-2009
[2009/12/17 18:28:11,  0] smbd/server.c:456(smbd_open_one_socket)
  smbd_open_once_socket: open_socket_in: Address already in use
[2009/12/17 18:28:11,  0] smbd/server.c:456(smbd_open_one_socket)
  smbd_open_once_socket: open_socket_in: Address already in use
[2009/12/17 18:30:23,  0] smbd/server.c:1068(main)
  smbd version 3.4.0 started.
  Copyright Andrew Tridgell and the Samba Team 1992-2009
[2009/12/17 18:30:23,  0] smbd/server.c:456(smbd_open_one_socket)
  smbd_open_once_socket: open_socket_in: Address already in use
[2009/12/17 18:30:23,  0] smbd/server.c:456(smbd_open_one_socket)
  smbd_open_once_socket: open_socket_in: Address already in use
[2009/12/17 18:32:00,  0] smbd/server.c:1068(main)
  smbd version 3.4.0 started.
  Copyright Andrew Tridgell and the Samba Team 1992-2009
[2009/12/17 18:32:00,  0] smbd/server.c:456(smbd_open_one_socket)
  smbd_open_once_socket: open_socket_in: Address already in use
[2009/12/17 18:32:00,  0] smbd/server.c:456(smbd_open_one_socket)
  smbd_open_once_socket: open_socket_in: Address already in use
[2009/12/17 18:33:06,  0] smbd/server.c:1068(main)
  smbd version 3.4.0 started.
  Copyright Andrew Tridgell and the Samba Team 1992-2009
[2009/12/17 18:33:06,  0] smbd/server.c:456(smbd_open_one_socket)
  smbd_open_once_socket: open_socket_in: Address already in use
[2009/12/17 18:33:06,  0] smbd/server.c:456(smbd_open_one_socket)
  smbd_open_once_socket: open_socket_in: Address already in use
[2009/12/17 18:33:43,  0] smbd/server.c:1068(main)
  smbd version 3.4.0 started.
  Copyright Andrew Tridgell and the Samba Team 1992-2009
[2009/12/17 18:33:44,  0] smbd/server.c:456(smbd_open_one_socket)
  smbd_open_once_socket: open_socket_in: Address already in use
[2009/12/17 18:33:44,  0] smbd/server.c:456(smbd_open_one_socket)
  smbd_open_once_socket: open_socket_in: Address already in use

In log.nmbd nothing major.

  *****
[2009/12/17 18:33:40,  0] nmbd/nmbd.c:71(terminate)
  Got SIGTERM: going down...
[2009/12/17 18:33:43,  0] nmbd/nmbd.c:854(main)
  nmbd version 3.4.0 started.
  Copyright Andrew Tridgell and the Samba Team 1992-2009
[2009/12/17 18:33:43,  0] nmbd/nmbd_nameregister.c:491(register_name)
  register_name: NetBIOS name LIBERTUS-COGNATIO is too long. Truncating to LIBERTUS-COGNAT
[2009/12/17 18:33:43,  0] nmbd/nmbd_nameregister.c:491(register_name)
  register_name: NetBIOS name LIBERTUS-COGNATIO is too long. Truncating to LIBERTUS-COGNAT
[2009/12/17 18:33:43,  0] nmbd/nmbd_nameregister.c:491(register_name)
  register_name: NetBIOS name LIBERTUS-COGNATIO is too long. Truncating to LIBERTUS-COGNAT
[2009/12/17 18:34:06,  0] nmbd/nmbd_become_lmb.c:395(become_local_master_stage2)
  *****
  Samba name server LIBERTUS-COGNATIO is now a local master browser for workgroup G604T_WIRELESS on subnet 192.168.1.251
  *****

But the Windows machines are unable to see the machine, or it's shares on the LAN.

Attached is the smb.conf, the directories I am sharing exist, the shared dir is chmod 777.