Comment 4 for bug 946755

Ok, some progress.

I edited the conf file

sudo nano /etc/lightdm/lightdm.conf

Then added the last line below which will allow a username and password combination to be explicitly supplied (reboot after making the change).

[SeatDefaults]
greeter-session=unity-greeter
user-session=ubuntu
autologin-user=
greeter-show-manual-login=true

However, I still cannot login as an Active Directory user (i.e. Windows login) even though I put in the correct username and password.