I have Ubuntu 12.04.1.
Last time I did nothing especial, but suddenly some problem appear:
I have a login screen (using lightdm), when I attempt a login, I get a console session and returned to the login screen. I see that it is a known issue, so I tried everything from following steps:
To removed .XAuthority
Configure to use gdm
Reinstall lightdm
To include my user to nopasswdlogin group
But nothing help...

So, these are errors from /var/log/auth.log:

Oct  3 01:11:48 alphabet-2 lightdm: pam_unix(lightdm:session): session opened for user lightdm by (uid=0)
Oct  3 01:11:48 alphabet-2 lightdm: pam_ck_connector(lightdm:session): nox11 mode, ignoring PAM_TTY :0
Oct  3 01:11:48 alphabet-2 lightdm: pam_succeed_if(lightdm:auth): requirement "user ingroup nopasswdlogin" not met by user "andrey"
Oct  3 01:11:48 alphabet-2 dbus[704]: [system] Rejected send message, 2 matched rules; type="method_call", sender=":1.35" (uid=104 pid=1709 comm="/usr/lib/indicator-datetime/indicator-datetime-ser") interface="org.freedesktop.DBus.Properties" member="GetAll" error name="(unset)" requested_reply="0" destination=":1.14" (uid=0 pid=1169 comm="/usr/sbin/console-kit-daemon --no-daemon ")

Any ideas?