Failed to load session “ubuntu” problem

I could not login to my Ubuntu Desktop after having some new theme related packages installed on.

got this error message "Failed to load session"

google it, found it may be related with the compiz packages
uninstall all related compiz packages, then retry after reboot. It works.

Boot Ubuntu as normal
on log-in screen, try to Ctrl - Alt - F1
Then login to the console using the account and password.
Then try the following commands:

  sudo apt-get update
  sudo apt-get remove compiz*
  sudo apt-get install unity-2d
  sudo apt-get install compizconfig-settings-manager
  sudo apt-get install compiz-plugins-extra
  sudo shutdown -r now

after the reboot, It is OK to login again.