Comment 4 for bug 1240336

And trying to start the agent produces:

:~/.config/geany$ /usr/lib/policykit-1-gnome/polkit-gnome-authentication-agent-1

(polkit-gnome-authentication-agent-1:5688): polkit-gnome-1-WARNING **: Unable to determine the session we are in: No session for pid 5688

I don't see any polkit warning in my ~/.xsession-errors. It looks like this:

Script for ibus started at run_im.
Script for auto started at run_im.
Script for default started at run_im.
init: at-spi2-registryd main process ended, respawning
init: at-spi2-registryd main process ended, respawning
init: at-spi2-registryd main process ended, respawning
init: at-spi2-registryd main process ended, respawning
init: at-spi2-registryd main process ended, respawning
init: at-spi2-registryd main process ended, respawning
init: at-spi2-registryd main process ended, respawning
init: at-spi2-registryd main process ended, respawning
init: at-spi2-registryd main process ended, respawning
init: at-spi2-registryd main process ended, respawning
init: at-spi2-registryd respawning too fast, stopped

There is a post that has been somewhat helpful in thinking of things to try at:

http://askubuntu.com/questions/303309/cant-mount-usb-devices-shut-down-etc-as-a-user