unity-greeter locks user out

[CristianCantoro]

Just upgraded to Ubuntu 11.10 beta2 from Ubuntu 11.04. Logging in with my user account and password. Screen gets black, I can see boot messages (but no hint of errors whatsoever) and then I am presented again with the login screen. Changing console (tty2) I can login. Purging unity-greeter and then launching gdm I can manage to login even if it seem my user preferences are gone. As I have said no hint are given to the user.

[Robert Ancell (robert-ancell)]

Could you check ~/.Xauthority is not root owned? If so, please delete it from a text login then log in from lightdm.

[CristianCantoro (cristiancantoro)]

I have reinstalled unity-greeter, checked that ~/.Xauthority was owned by my user and now I can login. So this issue is fixed for me.
Thanks for your help.

[Incen (sesquipedalian-demagogue)]

I just encountered and resolved this bug (running unity-greeter 0.2.8-0ubuntu1.3).

Autologin failed and logging in from the display manager just flashed a console and threw me back to the login screen.
Logging in as Guest worked fine.

The root cause seems to have been running sudo startx yesterday. This gave ownership of .Xauthority to root.

Deleting .Xauthority did not work - it just resulted in a misconfigured X session like yesterday. Specifically, it tried to start a GNOME session, despite gnome not being installed or selected.
Switching to lightdm-gtk-greeter did not work - it exhibited the same behaviour as unity-greeter.
Switching to gdm did not work - it completely froze.
Installing and switching to kdm did work - It first attempted to start the GNOME session, but then allowed me to select Xubuntu. This also fixed lightdm.

It seems that my issue was not specific to unity-greeter, so I'll leave this note here for anyone facing similar difficulty.