I've installed the samba packages(3.4.0-3ubuntu5.1) from karmic-proposed
yesterday, and sadly it didn't improve anything at all.
I could join the domain with the client(I could do that with the version
released in karmic too though), but the user login still fails with the error:
The trust
My mistake.
I've previously edited two additional keys under the NetLogon section,
that were mentioned a howto before. Seems it doesn't work that way
anymore. After reseting those keys back to their original value domain
logon works again as before in jaunty, so the release in karmic-proposed