Comment 7 for bug 987791

Nope, I have everything fully updated, except for Cinnamon itself. I have the latest stable instead of the latest nightly.
The updated version from April 27th caused the Cinnamon-session to no longer work.

I had to force version from Cinnamon 1.4.0-20120427044007-precise to 1.4.0-2ubuntu1~precise1 to get it to work again.

http://ubuntuforums.org/showthread.php?p=11879328