[Petya V4sechkin]

Peresvet_2005, если погуглить, можно что-нибудь найти.
Например:

I finally found the problem. When I added a new user via the phpldapadmin interface I always left the sambaSID value blank. This was causing the message.

Или:

I had this problem while using SAMBA as PDC. The only way I found out to get rid of these errors messages was by disabling certificates. To disable annoying Event Viewer notifications about "Automatic certificate enrollment for local system failed to contact the active directory" every eight hours, locate the Computer Configuration -> Windows Settings -> Security Settings -> Public Key Policies branch and select "Do not enroll certificates automatically" under Autoenrollment Settings. Note that this policy will not be available until after the XP machine has joined the domain.