Account Lockout

[Micke]

Hello.

Having some problems with account beeing locked out time
and time again.
Getting the following message from the EventLog:
The Security System detected an attempted downgrade
attack for server cifs/underdog. The failure code from
authentication protocol Kerberos was "There are currently
no logon servers available to service the logon request.
(0xc000005e)".

It's the LSASRV source reporting this error.

Anyone got any suggestions of what to do?
Or where to start looking?
Windows XP sp1, in AD-domain.

Would be nice with some help.

Thanx in advance.

Regards
/micke