错误failed to load session ubuntu的解决办法

http://www.jsfoot.com/jquery/tooltips/

http://code.google.com/p/title24/source/browse/trunk/t24-nav/t24nav/?r=23

http://www.nickstakenburg.com/projects/prototip2/

http://www.nickstakenburg.com/projects/prototip2/images/prototip/styles/protogrey/close.png

http://www.jsfoot.com/jquery/demo/2011-02-20/29.html

I just did a clean install of 12.04 and everything went fine. Then I started adding some software packages and was asked to restart so I did.

But then I got the error "failed to load session ubuntu".
So after searching around a bit I found a post that said to do the following:

sudo apt-get update
sudo apt-get install ubuntu-desktop
sudo apt-get -f install
sudo dpkg-reconfigure ubuntu-desktop
sudo reboot
sudo apt-get install gnome-session
sudo apt-get install lightdm
sudo apt-get install unity-greeter
sudo dpkg-reconfigure lightdm