4.1.7 Slow To Respond To SMB Network Discovery...

I've just reproduced the issue, again.
In smbd.log I've found the following entries (created during the relevant time frame):

[2011/02/14 18:45:24, 0] lib/util_sock.c:get_peer_addr(1334)
  getpeername failed. Error was Transport endpoint is not connected
[2011/02/14 18:45:24, 0] lib/util_sock.c:get_peer_addr(1334)
  getpeername failed. Error was Transport endpoint is not connected
[2011/02/14 18:45:24, 0] lib/util_sock.c:write_data(562)
  write_data: write failure in writing to client 0.0.0.0. Error Connection reset by peer
[2011/02/14 18:45:24, 0] lib/util_sock.c:send_smb(871)
  Error writing 4 bytes to client. -1. (Connection reset by peer)
[2011/02/14 18:45:51, 2] auth/auth.c:check_ntlm_password(309)
  check_ntlm_password:  authentication for user [xxx] -> [xxx] -> [xxx] succeeded
[2011/02/14 18:46:24, 0] lib/util_sock.c:get_peer_addr(1334)
  getpeername failed. Error was Transport endpoint is not connected
[2011/02/14 18:46:24, 0] lib/util_sock.c:write_data(562)
  write_data: write failure in writing to client 192.168.2.115. Error Connection reset by peer
[2011/02/14 18:46:24, 0] lib/util_sock.c:send_smb(871)
  Error writing 4 bytes to client. -1. (Connection reset by peer)
[2011/02/14 18:46:50, 2] auth/auth.c:check_ntlm_password(309)
  check_ntlm_password:  authentication for user [xxx] -> [xxx] -> [xxx] succeeded
[2011/02/14 18:47:30, 0] smbd/server.c:main(942)
  smbd version 3.0.37 started.
  Copyright Andrew Tridgell and the Samba Team 1992-2009
[2011/02/14 18:47:47, 2] auth/auth.c:check_ntlm_password(309)
  check_ntlm_password:  authentication for user [xxx] -> [xxx] -> [xxx] succeeded

Remarkable: the "lib/util_sock.c" error entries.
18:45:24 - 18:46:50: 86 seconds waiting time. That's how long it took for the SMB network discovery.
([xxx] - I've replaced the actual username by 'xxx', '192.168.2.115' is the IP address of the PC requesting the share from the NAS)

At 18:47 I've stopped and restarted the CIFS service, see daemon.log (same in system.log):

Feb 14 18:47:08 NAS avahi-daemon[694]: Got SIGHUP, reloading.
Feb 14 18:47:08 NAS avahi-daemon[694]: Service group file /etc/avahi/services/cifs.service vanished, removing services.
Feb 14 18:47:09 NAS smbd[3061]: PAM pam_putenv: delete non-existent entry; KRB5CCNAME
Feb 14 18:47:31 NAS avahi-daemon[694]: Got SIGHUP, reloading.
Feb 14 18:47:31 NAS avahi-daemon[694]: Loading service file /etc/avahi/services/cifs.service.
Feb 14 18:47:32 NAS avahi-daemon[694]: Service "NAS (CIFS)" (/etc/avahi/services/cifs.service) successfully established.
Feb 14 18:47:59 NAS smbd[3189]: PAM pam_putenv: delete non-existent entry; KRB5CCNAME

After that, access to the shares worked - and in smbd.log there are no more "lib/util_sock.c" error entries.
("NAS" is the hostname of my ReadyNAS Duo)

network_settings.log does not show any network problems:

eth0      Link encap:Ethernet  HWaddr xx:xx:xx:xx:xx:xx  
          inet addr:192.168.2.100  Bcast:192.168.2.255  Mask:255.255.255.0
          UP BROADCAST RUNNING MULTICAST  MTU:7936  Metric:1
          RX packets:4992 errors:0 dropped:0 overruns:0 frame:0
          TX packets:2886 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:2049130 (1.9 MiB)  TX bytes:3491373 (3.3 MiB)
          Interrupt:41 

lo        Link encap:Local Loopback  
          inet addr:127.0.0.1  Mask:255.0.0.0
          UP LOOPBACK RUNNING  MTU:16436  Metric:1
          RX packets:38918 errors:0 dropped:0 overruns:0 frame:0
          TX packets:38918 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0 
          RX bytes:2697778 (2.5 MiB)  TX bytes:2697778 (2.5 MiB)

JUMBO_FRAMES_eth0=1
SPEED_DUPLEX_eth0=AUTO_NEGOTIATION