[Samba] NO_LOGON_SERVERS error

[Emilio Casbas]

Hello,

We have a 3.0.21c samba server in a PDC role with ldap as the backend 
database, the server
has been working without any problem for several weeks, but today it's 
started showing this log message:

[2006/11/20 09:40:48, 0] tdb/tdbutil.c:tdb_log(772)
  tdb(/usr/local/etc2/samba_SACOU/private/secrets.tdb): tdb_lock failed 
on list 100 ltype=1 (Interrupted system call)
[2006/11/20 09:40:48, 0] 
tdb/tdbutil.c:tdb_chainlock_with_timeout_internal(82)
  tdb_chainlock_with_timeout_internal: alarm (10) timed out for key 
PDC10 in tdb /usr/local/etc2/samba/private/secrets.tdb
[2006/11/20 09:40:48, 0] tdb/tdbutil.c:tdb_log(772)

some users couldn't do log in on the PDC, this is the related log;
[2006/11/20 09:41:08, 0] auth/auth_domain.c:domain_client_validate(206)
  domain_client_validate: Domain password server not available.
[2006/11/20 09:41:08, 2] auth/auth.c:check_ntlm_password(317)
  check_ntlm_password:  Authentication for user [trendo] -> [trendo] 
FAILED with error NT_STATUS_NO_LOGON_SERVERS
[2006/11/20 09:41:08, 2] smbd/server.c:exit_server(614)
  Closing connections

but surprinsigly other users could do log in on the PDC while the 
previous error keeps on the logs:
[2006/11/20 09:41:08, 2] auth/auth.c:check_ntlm_password(307)
  check_ntlm_password:  authentication for user [evamolina] -> [evam] -> 
[evam] succeeded
[2006/11/20 09:41:08, 1] smbd/service.c:make_connection_snum(693)
  fisiop (159.237.150.139) connect to service disco1 initially as user 
evam (uid=100298, gid=203) (pid 7939)
[2006/11/20 09:41:08, 2] smbd/server.c:exit_server(614)
  Closing connections

Any ideas?

Regards.
Emilio C.