Comment 7 for bug 1074657

This looks to be caused by improper session launch.

How to reproduce this problem:
1) open a terminal and check what your DISPLAY variable is set at and write it down:
echo $DISPLAY
NOTICE: I assume your DISPLAY variable is set to :0
If not, please use the variable that you wrote down instead
2) change to vt1 via ctrl+alt+f1
3) login
4) replace your shell via:
4a) for Unity:
DISPLAY=:0 unity --replace
-- or --
3b) for Gnome Shell:
DISPLAY=:0 gnome-shell --replace
4) go back to your shell (vt7) via ctrl+alt+f7 and wait a few seconds while your shell restarts

You should now experience the "Authorization failed" issue.

Open up Run command via alt+f2 and start your shell:
a) for Unity:
unity --replace
b) for Gnome Shell:
gnome-shell --replace

The "Authorization failed" issue should not longer exist.

At first I thought this was a polkitd issue, but alas, polkitd is always running, even when experiencing the issue:
/usr/lib/policykit-1/polkitd --no-debug

dbus-daemon is also always running.

It seems like something with the DISPLAY is not getting properly handled.