I'm running Xubuntu 12.04 (I installed using the alternative installer.) running in Virtaulbox 4.1.20

My issue is with the login screen (lightdm-gtk-greeter). It usually runs just fine, and allows users to log in and out but it will hang if the user presses the cancel button. The interface is still working (ie, shutdown menu is still available, I can switch to a different tty) but the username or password field (depending on when the button is hit) is disabled. Restarting lightdm will reset the screen, but the problem still exists.

The issue is only with the cancel button. The login, session, and language buttons/menus as well as the accessibility and shutdown menu appear to work normally.

I've modified some of the config files for lighdm-gtk-greeter, specifically /etc/lightdm/lighdm-gtk-greeter.conf to change the background image and /etc/lightdm/lightdm.conf to disable the user list. I did not check to see if the error existed before the changes took place. The changes have been restored the default settings but the problem persists.

Here is the output of /var/log/lightdm/lightdm.log when the screen is hung:

[+0.00s] DEBUG: Logging to /var/log/lightdm/lightdm.log
[+0.00s] DEBUG: Starting Light Display Manager 1.2.1, UID=0 PID=2072
[+0.00s] DEBUG: Loaded configuration from /etc/lightdm/lightdm.conf
[+0.00s] DEBUG: Using D-Bus name org.freedesktop.DisplayManager
[+0.00s] DEBUG: Registered seat module xlocal
[+0.00s] DEBUG: Registered seat module xremote
[+0.00s] DEBUG: Adding default seat
[+0.00s] DEBUG: Starting seat
[+0.00s] DEBUG: Starting new display for greeter
[+0.00s] DEBUG: Starting local X display
[+0.02s] DEBUG: Using VT 7
[+0.02s] DEBUG: Activating VT 7
[+0.03s] DEBUG: Logging to /var/log/lightdm/x-0.log
[+0.04s] DEBUG: Writing X server authority to /var/run/lightdm/root/:0
[+0.04s] DEBUG: Launching X Server
[+0.05s] DEBUG: Launching process 2078: /usr/bin/X :0 -auth /var/run/lightdm/root/:0 -nolisten tcp vt7 -novtswitch
[+0.05s] DEBUG: Waiting for ready signal from X server :0
[+0.05s] DEBUG: Acquired bus name org.freedesktop.DisplayManager
[+0.05s] DEBUG: Registering seat with bus path /org/freedesktop/DisplayManager/Seat0
[+0.28s] DEBUG: Got signal 10 from process 2078
[+0.28s] DEBUG: Got signal from X server :0
[+0.28s] DEBUG: Connecting to XServer :0
[+0.29s] DEBUG: Starting greeter
[+0.29s] DEBUG: Started session 2082 with service 'lightdm', username 'lightdm'
[+0.36s] DEBUG: Session 2082 authentication complete with return value 0: Success
[+0.36s] DEBUG: Greeter authorized
[+0.36s] DEBUG: Logging to /var/log/lightdm/x-0-greeter.log
[+0.36s] DEBUG: Session 2082 running command /usr/lib/lightdm/lightdm-greeter-session /usr/sbin/lightdm-gtk-greeter
[+0.58s] DEBUG: Greeter connected version=1.2.1
[+0.58s] DEBUG: Greeter connected, display is ready
[+0.58s] DEBUG: New display ready, switching to it
[+0.58s] DEBUG: Activating VT 7
[+1.04s] DEBUG: Greeter start authentication for andrew
[+1.04s] DEBUG: Started session 2137 with service 'lightdm', username 'andrew'
[+1.09s] DEBUG: Session 2137 got 1 message(s) from PAM
[+1.09s] DEBUG: Prompt greeter with 1 message(s)
[+17.24s] DEBUG: Cancel authentication
[+17.24s] DEBUG: Session 2137: Sending SIGTERM