I'd like to share a 3 hours hint success here, because I used the keywords "ubuntu logout bug" and first landed here.
But my answer was here: ".Xauthority sometimes owned by root, which blocks login" https://bugs.launchpad.net/ubuntu/+source/lightdm/+bug/871667/comments/30 -- You received this bug notification because you are a member of Ubuntu-X, which is subscribed to nvidia-graphics-drivers in Ubuntu. https://bugs.launchpad.net/bugs/980519 Title: Random log off in Ubuntu 12.04 LTS To manage notifications about this bug go to: https://bugs.launchpad.net/unity/+bug/980519/+subscriptions _______________________________________________ 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