Aha. Bug 546578 led me to bug 555870. I caused the problem to happen, SSH'ed to the machine, found out which X display was active: $ /usr/bin/ck-list-sessions: Session2: ..snip.. active = TRUE x11-display = ':0' ..snip..
Then did: $ export DISPLAY=:0 and then: $ sudo xrandr --output VGA1 --gamma 1:1:1 (Your output name may differ use xrandr w/o argument to find out) This restored the display. For me at least, this problem is related to bug 555870. Others should try the above also to verify if they are affected by the same bug. -- Logout after switch user cause black screen https://bugs.launchpad.net/bugs/561538 You received this bug notification because you are a member of Ubuntu-X, which is subscribed to xorg-server in ubuntu. _______________________________________________ Mailing list: https://launchpad.net/~ubuntu-x-swat Post to : ubuntu-x-swat@lists.launchpad.net Unsubscribe : https://launchpad.net/~ubuntu-x-swat More help : https://help.launchpad.net/ListHelp