Comment 4 for bug 247342

You are still using the deprecated -i810 driver. Please regenerate your xorg.conf with the command >>sudo dpkg-reconfigure xserver-xorg<< without (>><<). Confirm every question with enter and logout afterwards. After the login the display should working out of the box if it was connected on start.
If not please attach the file /var/log/Xorg.0.log.