samba - Mar 2010 - Occasional printing to /dev/null with Windows 7

Hello!

I'm looking after a small office with several PCs that is using Samba for
many years now; however it was Samba 3.2.x
with Windows 2000 clients.

Now they bought entirely new PCs, of course with Windows 7 pre-installed. I
managed to successfully move the setup over
to Samba 3.3.10, 3.4.5 and now 3.4.6. Everything is working fine, however one
problem stubbornly resists to go away:
"Ghost Printing".

That phrase means that a print job sent to a samba printer is just spooled
normally, it appears in the print job list of
the Windows client, seemingly is printed and vanishes from the print job list.
No error is displayed, the printer is
shown as "ready" and can be seen in the "Network
Neighborhood" just normally.

However, the print job that was spooled never gets printed. Printing system is
CUPS and it can be deduced from the CUPS
logs that the job was never given to CUPS.

What drives me mad is that this behavior is sporadic and somehow connected to
the logon session of the user. It may
happen that the user can print just fine several days in a row and it stops
working the next day. Often it helps to just
reboot the Windows client PC (just logging the user off and on again leads to
"The User Profile Service failed the logon
- User profile cannot be loaded" error in 80% of the cases).

Well; of course i combed through the samba smbd.log file at several log levels
but honestly, i did not really recognize
a error message that is related to cups printing (Samba logs are a bit too much
on the chatty side for me...).

So, did anybody see similar problems? Or anything i could try to close in on the
error?

Regards,
  Peter