Same problem on my laptop, started right after upgrade from 15.10 to 16.04. Happens right after I plug external monitor to to HDMI socket, system freezes and not responding to any actions from keyboard and touchpad. I'm using Intel® HD Graphics 520.
-- You received this bug notification because you are a member of Ubuntu-X, which is subscribed to xorg in Ubuntu. https://bugs.launchpad.net/bugs/1559308 Title: Plugging HDMI screen in causes system hang To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/xorg/+bug/1559308/+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