I'm pretty sure you're dealing with
this bug. Let's first try upgrading the xorg server stack for your i915 Intel Graphics. To do that we're going to:
(1) Add the uberstudent.net
heraclitus-backports repository to your machine (which is already present on your machine but not enabled, since your system is one that has been upgraded from 4.0 or 4.1 to 4.3)
(2) Update the repository info on your machine
(3) Install the new packages.
Please open a terminal and run the following lines, one line at a time:
Code:
sudo cp -fv /usr/share/uberstudent/uberstudentsources/heraclitus/* /usr/share/uberstudentsources/heraclitus
sudo cp -fv /usr/share/uberstudentsources/heraclitus/official-package-repositories.list /etc/apt/sources.list.d
sudo cp -fv /usr/share/uberstudent/uberstudentsources/overwrites/preferences-heraclitus /etc/apt/preferences
sudo apt-get update
sudo apt-get -s install --install-recommends linux-generic-lts-vivid xserver-xorg-core-lts-vivid xserver-xorg-lts-vivid xserver-xorg-video-all-lts-vivid xserver-xorg-input-all-lts-vivid libwayland-egl1-mesa-lts-vivid
Then, reboot and let me know if this fixes the issue. If not, we'll proceed to add a few lines to your 20-intel.conf file.