Quote Originally Posted by rusty725 View Post
well I still get lockups even with gnome shell 3.4.2. so far didn't find any solution. somebody please help
I had the same problem with the Gnome shell. I fixed it by logging into a Unity session, removing the Gnome shell and its configuration files by running

sudo apt-get purge gnome-shell
This removes your Gnome tweak tool as well. Re-install by running
sudo apt-get install gnome-shell gnome-tweak-tool
Hope this fixes your problem.