samba - Jan 2002 - Authentication - all pipes busy - how to increase?

Hello, all!

Sometime I see this error in smb.log:
- Cut -
[2002/01/15 13:23:17, 0] rpc_client/cli_pipe.c:cli_nt_session_open(1204)
  cli_nt_session_open: cli_nt_create failed on pipe \NETLOGON to machine 
DC001.  Error was ERRDOS - ERRpipebusy (A
ll instances of the requested pipe are busy.)
[2002/01/15 13:23:17, 0] 
smbd/password.c:connect_to_domain_password_server(1363)
  connect_to_domain_password_server: unable to open the domain client 
session to machine DC001. Error was : ERRDOS
 - ERRpipebusy (All instances of the requested pipe are busy.).
- Cut -
May someone describe, that this mean?
How to increase number of pipe instances?

Regards!
  Alexander Dubinin.