Comment 6 for bug 874145

A suggesttion was made using terminal to restart gdm. I tried various methods but all failed, here is a log of the attempts:

emanuel@EAlaptop:~$ sudo /etc/init.d/gdm restart
[sudo] password for emanuel:
Rather than invoking init scripts through /etc/init.d, use the service(8)
utility, e.g. service gdm restart

Since the script you are attempting to invoke has been converted to an
Upstart job, you may also use the stop(8) and then start(8) utilities,
e.g. stop gdm ; start gdm. The restart(8) utility is also available.
gdm start/running, process 2183
emanuel@EAlaptop:~$ gdm start/running, process 2183

** (gdm-binary:2310): WARNING **: Failed to acquire org.gnome.DisplayManager: Connection ":1.82" is not allowed to own the service "org.gnome.DisplayManager" due to security policies in the configuration file

** (gdm-binary:2310): WARNING **: Could not acquire name; bailing out
emanuel@EAlaptop:~$ service gdm restart
restart: Rejected send message, 1 matched rules; type="method_call", sender=":1.83" (uid=1000 pid=2312 comm="restart gdm ") interface="com.ubuntu.Upstart0_6.Job" member="Restart" error name="(unset)" requested_reply="0" destination="com.ubuntu.Upstart" (uid=0 pid=1 comm="/sbin/init")
emanuel@EAlaptop:~$ stop gdm; start gdm
stop: Rejected send message, 1 matched rules; type="method_call", sender=":1.84" (uid=1000 pid=2317 comm="stop gdm ") interface="com.ubuntu.Upstart0_6.Job" member="Stop" error name="(unset)" requested_reply="0" destination="com.ubuntu.Upstart" (uid=0 pid=1 comm="/sbin/init")
start: Rejected send message, 1 matched rules; type="method_call", sender=":1.85" (uid=1000 pid=2318 comm="start gdm ") interface="com.ubuntu.Upstart0_6.Job" member="Start" error name="(unset)" requested_reply="0" destination="com.ubuntu.Upstart" (uid=0 pid=1 comm="/sbin/init")
emanuel@EAlaptop:~$ gdm start/running, process 2183

** (gdm-binary:2320): WARNING **: Failed to acquire org.gnome.DisplayManager: Connection ":1.86" is not allowed to own the service "org.gnome.DisplayManager" due to security policies in the configuration file

** (gdm-binary:2320): WARNING **: Could not acquire name; bailing out
emanuel@EAlaptop:~$