Originally found here: http://www.nnbfn.net/tag/ubuntu/
Here is the Exerpt: CRITICAL: cannot initialize libpolkit
Here is the posting:
The error is triggered by the update-modt cron job which runs ever 10 minutes.
This is a bug in Intrepid. console-kit-daemon requires PolicyKit as a dependancy, but Intrepid (Server AMD64) does not install it when it installs console-daemon-kit.
The simple fix is to install policykit.
sudo apt-get install policykit
Next run of the update-motd job and the error is gone.