I played a bit with my 13.10 installation and managed to break Lightdm :/
I had Lubuntu/Xubuntu/Ubuntu installed and tried to remove Ubuntu following http://www.psychocats.net/ubuntu/purelubuntu
Now I can't get to my desktop. At boot I have the following items failing :
Starting load fallback graphics devices
Starting Lightdm Display Manager
Starting Send an event to indicate plymouth is up
Thank you for the help.