RE: The message above comes at every request from the Linux machine (every 5 minutes on this installation). If I am validating a user, the same message is shown for the user like this (user name validated=test): Pre-authentication failed: User Name: test$ User ID: KK\test$ Service Name: krbtgt/KK.LOCAL Pre-Authentication Type: 0x0 Failure Code: 0x19 Client Address: 1.2.3.4 Messages logged on behalf of a user may be disabled by deactivating pre-authentification for each user. But I cannot find any place in ActiveDirectory to disable it for the machine account. What is missing ? Is it possible to deactivate pre-authentification on the Linux (or Windows) side to avoid these messages ? The Solution is to use the Active Directory tool "Users and Computers" Select "Computers" and open the SAMBA computer entry. Select Properties | Delegation and "Trust this computer for delegation to any service [or get granuloar and trust it to specific services only..] (Default is "Do not trust this computer for delegation) Greg Hanks ------------------------ +001 (860) 349-4440 Fax (860) 349-4442