I installed Unity 5.0 to test on my 11.10 setup and I've just removed it recently. Restarting the computer, I can't logon to my desktop now. I insert my password, then a black screen comes up and then it goes back to the login screen.
sudo add-apt-repository ppa:unity-team/stages sudo apt-get update sudo apt-get dist-upgrade
sudo ppa-purge ppa:unity-team/stages