Comment 54 for bug 749817

I have a Samsung qx310 and I have been affected by the exact same behaviour - always a black screen in the dock and while connecting the monitor directly with the laptop.
I installed the kernel suggested in comment #45 but when I rebooted I got the "failed to get i915 symbol error"
Then I swapped back to the old 2.6.35-29-generic kernel to understand if by any chance unity would work on top of it. The answer is: kid of. It works perfectly until you plug in the hdmi connector, then the monitor is recognized but work in mirror mode only. Picking any other monitor configuration (either side by side or external monitor only) leads to refresh problems and/or part of the window(s) that are not properly drawn.
At the end I tried to launch an ubuntu classic session and within it, everything got back to normal.
So I'm assuming that the issue is due to both some kind of regression bug in the 2.6.38 kernel and to how unity uses draws the windows when it comes to external monitors.
I can reproduce it anytime, so if it would be of any interest/use I can post my xorg logs