Comment 9 for bug 46193

I found out that the lines in syslog are most likely to be produced by gdmsetup:

[terminal output]
root@neo:~# gdmsetup
  Failed to connect to socket, sleep 1 second and retry
  Trying failed command again. Try 2 of 5.
  Failed to connect to socket, sleep 1 second and retry
  Trying failed command again. Try 3 of 5.
  Failed to connect to socket, sleep 1 second and retry
  Trying failed command again. Try 4 of 5.
  Failed to connect to socket, sleep 1 second and retry
  Trying failed command again. Try 5 of 5.
  Command failed 5 times, aborting.
Kon het configuratiebestand van GDM niet benaderen.
root@neo:~#
[/terminal output]

The last line is dutch and means as much as: Could not approach (find?) the GDM configuration file.
Still all permissions are setup right. I even tried to give the gdm group write access to the configuration files, but that also didn't work.