In my case the problem was related to the ldap nss authentication. dbus- daemon is running as messagebus user while libnss-ldap.conf is not readable by anyone except root (600) - so dbus-daemon could not authenticate. Changing permissions to 644 fixed the connection problem.
-- gnome-settings-daemon crashes at login https://launchpad.net/bugs/61381 -- desktop-bugs mailing list desktop-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/desktop-bugs
