Comment 39 for bug 856810

In my case also manual symlinking of /var/run->/run and /var/lock-/run/lock fixed my issues.
In my case the problem was caused by dbus. As long as I did not symlink /var/run and /var/lock dbus could not be started and prevented practically anything else to run.
Although dbus created /var/run/dbus/pid and /var/run/dbus/system_bus_socket but the process listed in pid was never running. After removing the pid, restarting dbus sometimes worked sometimes not but when dbus could be started gdm or even lightdm could be started successfully and gui was working fine.

So probably you can simulate this error having
/var/run, /var/lock, /run, /run/lock all as different directories and if dbus fails with this config then there you go.