I am also affected by this issue Running 12.04 full updated.
Same scenario as above Logged in as account 1 - autologin enabled Switch to Account 2 - sometimes make it, sometimes get the black screen Only resolution is CTRL+ALT+DEL (complete restart) or CTRL + ALT+F7 to go back to Account 1. This problem has manifest itself in the last 24 hours, of which only three changes have occurred. - Update of new h/w - was working after new CPU/Mobo/Ram installation - Update of new VM's using Virtual Box - again was working - Install of Synergy and configured between Ubuntu and Mac. - switching off Synergy has not resolved the issue. The first time it happened I wasn't aware of CTRL+ALT+F7 so done a reboot. Issue was resolved for a while Tail end of lightdm.log - note AnneMarie is Account 2. I notice that it spawns 26350 to switch, but that exists with a value of 1 and stops. No reasoning why [+20862.79s] DEBUG: Switching to user annemarie [+20862.79s] DEBUG: Starting new display for greeter with user annemarie selected [+20862.79s] DEBUG: Starting local X display [+20862.79s] DEBUG: Using VT 8 [+20862.79s] DEBUG: Logging to /var/log/lightdm/x-1.log [+20862.79s] DEBUG: Writing X server authority to /var/run/lightdm/root/:1 [+20862.79s] DEBUG: Launching X Server [+20862.79s] DEBUG: Launching process 26350: /usr/bin/X :1 -auth /var/run/lightdm/root/:1 -nolisten tcp vt8 -novtswitch [+20862.79s] DEBUG: Waiting for ready signal from X server :1 [+20866.54s] DEBUG: Process 26350 exited with return value 1 [+20866.54s] DEBUG: X server stopped [+20866.54s] DEBUG: Removing X server authority /var/run/lightdm/root/:1 [+20866.54s] DEBUG: Releasing VT 8 [+20866.54s] DEBUG: Display server stopped [+20866.54s] DEBUG: Stopping display [+20866.54s] DEBUG: Display stopped -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1001221 Title: 12.04 black screen with blinking cursor when switching users To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/lightdm/+bug/1001221/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs