Did you install using 14.04.2 media? Then you're using the driver stack from 14.10. You could try using 'Option "AccelMethod" "uxa"' in xorg.conf (man intel), or update to vivid lts stack in trusty-proposed.
** Package changed: xorg (Ubuntu) => xserver-xorg-video-intel (Ubuntu) -- You received this bug notification because you are a member of Ubuntu-X, which is subscribed to xserver-xorg-video-intel in Ubuntu. https://bugs.launchpad.net/bugs/1472471 Title: XServer crash logs the user off randomly To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/xserver-xorg-video-intel/+bug/1472471/+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