samba - Nov 2010 - samba server in Microsoft Domain, many errors in logs

hi all, 

i'm not expert with Samba integration into domain.
I did setup many servers acting with local auth that were running very
fine.

We've a Windows 2008 acting as Domain controller.
So to not create more login/password to users, i decided to
authenticate using Active Directory.

The shares work, but sometimes users failed to access.

The server is running Debian stable Lennny.
The package is from backports (now 3.5.6 but errors were also present
in 3.4.7).

Sometimes (about 1/3), by testing from my linux box with smbclient,
i've got this error : 
Receiving SMB: Server stopped responding
session setup failed: Call timed out: server did not respond after
20000 milliseconds


If some can give me some advices it'll be great.


in log.winbindd-idmap , I've got these errors :


[2010/11/22 12:06:29.182129,  1]
winbindd/idmap_ad.c:143(ad_idmap_cached_connection_internal)
ad_idmap_init: failed to connect to AD [2010/11/22 12:06:29.182170,  1]
winbindd/idmap_ad.c:543(idmap_ad_sids_to_unixids) ADS uninitialized: No
logon servers [2010/11/22 12:06:31.621875,  1]
winbindd/idmap_ad.c:143(ad_idmap_cached_connection_internal)
ad_idmap_init: failed to connect to AD [2010/11/22 12:06:31.621907,  1]
winbindd/idmap_ad.c:543(idmap_ad_sids_to_unixids) ADS uninitialized: No
logon servers [2010/11/22 12:06:31.625732,  0]
winbindd/idmap.c:201(smb_register_idmap_alloc) idmap_alloc module tdb
already registered! [2010/11/22 12:06:31.625772,  0]
winbindd/idmap.c:149(smb_register_idmap) Idmap module passdb already
registered! [2010/11/22 12:06:31.625793,  0]
winbindd/idmap.c:149(smb_register_idmap) Idmap module nss already
registered! [2010/11/22 12:06:31.625836,  1]
winbindd/idmap.c:580(idmap_alloc_init) could not find idmap alloc
module ad [2010/11/22 12:06:31.627479,  0]
winbindd/idmap.c:201(smb_register_idmap_alloc) idmap_alloc module tdb
already registered! [2010/11/22 12:06:31.627520,  0]
winbindd/idmap.c:149(smb_register_idmap) Idmap module passdb already
registered! [2010/11/22 12:06:31.627540,  0]
winbindd/idmap.c:149(smb_register_idmap) Idmap module nss already
registered! [2010/11/22 12:06:31.627576,  1]
winbindd/idmap.c:580(idmap_alloc_init) could not find idmap alloc
module ad [2010/11/22 12:06:34.066277,  1]
winbindd/idmap_ad.c:143(ad_idmap_cached_connection_internal)
ad_idmap_init: failed to connect to AD [2010/11/22 12:06:34.066315,  1]
winbindd/idmap_ad.c:543(idmap_ad_sids_to_unixids) ADS uninitialized: No
logon servers [2010/11/22 12:06:36.505492,  1]
winbindd/idmap_ad.c:143(ad_idmap_cached_connection_internal)
ad_idmap_init: failed to connect to AD [2010/11/22 12:06:36.505531,  1]
winbindd/idmap_ad.c:543(idmap_ad_sids_to_unixids) ADS uninitialized: No
logon servers [2010/11/22 12:06:38.944794,  1]
winbindd/idmap_ad.c:143(ad_idmap_cached_connection_internal)
ad_idmap_init: failed to connect to AD [2010/11/22 12:06:38.944828,  1]
winbindd/idmap_ad.c:543(idmap_ad_sids_to_unixids) ADS uninitialized: No
logon servers [2010/11/22 12:06:41.383966,  1]
winbindd/idmap_ad.c:143(ad_idmap_cached_connection_internal)
ad_idmap_init: failed to connect to AD [2010/11/22 12:06:41.384007,  1]
winbindd/idmap_ad.c:543(idmap_ad_sids_to_unixids) ADS uninitialized: No
logon servers [2010/11/22 12:06:43.822633,  1]
winbindd/idmap_ad.c:143(ad_idmap_cached_connection_internal)
ad_idmap_init: failed to connect to AD [2010/11/22 12:06:43.822669,  1]
winbindd/idmap_ad.c:543(idmap_ad_sids_to_unixids) ADS uninitialized: No
logon servers [2010/11/22 12:06:46.261668,  1]
winbindd/idmap_ad.c:143(ad_idmap_cached_connection_internal)
ad_idmap_init: failed to connect to AD [2010/11/22 12:06:46.261713,  1]
winbindd/idmap_ad.c:543(idmap_ad_sids_to_unixids) ADS uninitialized: No
logon servers [2010/11/22 12:06:48.700737,  1]
winbindd/idmap_ad.c:143(ad_idmap_cached_connection_internal)
ad_idmap_init: failed to connect to AD [2010/11/22 12:06:48.700773,  1]
winbindd/idmap_ad.c:543(idmap_ad_sids_to_unixids) ADS uninitialized: No
logon servers