I installed Ubuntu-minimal and tried to install gnome 3 to see how it was. It seems to have installed ok and I've got to the gdm screen. However, there are no users listed, it just says "Other", and when I click that to try and login using my username and password it just greys out like it's trying to login but doesn't do anything (no hdd activity). Yet when I try a username that doesn't exist it says "Authentication failed"
2 Answers
I think you should install accountsservice :
sudo apt-get install accountsservice
It solved the problem for me :-)
Log into a Recovery console from Grub, drop to a root shell with Internet and install
sudo apt-get update; sudo apt-get install gnome3-session