The bug has been reported on https://bugs.launchpad.net/ubuntu/+source/xserver-xorg-video-intel/+bug/1421575
"Thinkpad X220 running vivid up to date.
Usually sits in docking station with external monitor.
Today I ran the laptop outside the docking station, and plugged it into the dock while running (which worked fine forever on utopic) but today it now freaks out.
I deleted ~/.config/monitors.xml to reset my display config
I restarted and logged in with both monitors active.
As soon as I change the display config doing the display corrupts, flickers and becomes unusable.
Here's a photo:- http://imgur.com/80LcmgV
Intel Corporation 2nd Generation Core Processor Family Integrated Graphics Controller [8086:0126] (rev 09) (prog-if 00 [VGA controller])
Subsystem: Lenovo Device [17aa:21da]
xorg log, https://launchpadlibrarian.net/197510967/XorgLog.txt
Similar corruption happens using an inspiron 11 3138 config on wily, when connecting a projector with hdmi the screen corrupts and things don't recover until the session is restarted
the syslog has those warnings
"kernel: [ 2006.138268] i915 0000:00:02.0: BAR 6: [??? 0x00000000 flags 0x2] has bogus alignment"
the inspiron video card is
00:02.0 VGA compatible controller: Intel Corporation Atom Processor Z36xxx/Z37xxx Series Graphics & Display (rev 0a) (prog-if 00 [VGA controller])
video showing the issue on https://www.youtube.com/watch?v=ElXAyX93Uqw