Comment 10 for bug 1212821

Looking at the gnome-session.log file it appears there were problems with OpenGL support in X at some point. That seems to have disabled the OpenGL compiz plugin.

I'd suggest running the Compiz Configuration Settings Manager (ccsm) and unselecting the Unity plugin (if it's checked) and the re-selecting it. That should (hopefully) reset the basic configuration required to run Unity.

(As for the ssh-related problem, I've run into that with recent builds where remote X clients (wrongly) create a ~/.Xauthority file that the local session cannot overwrite: try removing all ~/.Xauthority files).