Something after installing Cinnamon has screwed up my ability to use Unity and KDE on Ubuntu 13.10. When I try to log in to either I get an error that dbus could not start. Any ideas what has happened? When I try to log in to KDE I get: "Could not start D-Bus. Can you call qbus?"
Try removing Cinnamon from start up:
sudo rm -f /usr/share/upstart/sessions/cinnamon-se*