Finally a workaround was posted on Launchpad - I've been battling this bug for 11 months:
#sudo nano /usr/share/X11/xorg.conf.d/20-intel.conf
#Add the following lines Section "Device" Identifier "Intel Graphics" Driver "intel"
Option "AccelMethod" "uxa" EndSection
#reboot
Finally a workaround was posted on Launchpad - I've been battling this bug for 11 months:
#sudo nano /usr/share/ X11/xorg. conf.d/ 20-intel. conf
#Add the following lines
Section "Device"
Identifier "Intel Graphics"
Driver "intel"
Option "AccelMethod" "uxa"
EndSection
#reboot