this is a workaround for the lightdm "can't login" bug in lubuntu "alpha 2" release

[Karl Anliot]

all credit to head_victim in #lubuntu

Right now, all testers see after installing the alpha release is a
black screen with a "failed to load session ubuntu"

there is a workaround:

control+alt+f1  (if you are using a vm you will need to know secret
codes control+alt space, control+alt f1)
(login to the console)
sudo apt-get install lxdm
sudo reboot

alt+L to get past the error again
change the session to lubuntu
login