After do-release-upgrade to 14.04, unity has video problems: The right-hand one inch of the screen is blank, and after 15 seconds the monitor goes into power-save-mode (i.e., it's blank). The computer is still running; I recover from this by using Ctrl-Alt-F1 to go to a virtual terminal, where I log in and then kill the gnome-session process. This takes me back to a login screen, where I can start up an Fvwm session, where all is well.
I should stress that Fvwm runs fine, which tells me that the video drivers are still fine. I actually spend all my time in Fvwm, and only start up unity on the rare occasions that I have to access something not available via Fvwm, but it would be good to be able to run unity when I need it.
I've tried many suggestions I found on the web, including totally reinstalling unity. I've run
rm -rf .conf/dconf rm -rf .conf/.compiz-1 rm -rf .conf/gnome-disk-utility rm -rf .conf/gnome-session dconf reset -f /org/compiz unity-tweak-tool --reset-unity unity --reset-icons &disown apt-get install --reinstall gnome-session
I purged every package with the word "unity" in the name, and then reinstalled all of them, including having to install and run ccsm to get unity to be among the sessions offered by the login screen. I have a complete list of what was purged, reinstalled, and installed, but it's about 390 lines, so I'm not including it here.
To repeat the main problem: It's acting as if unity is switching to some modeline that the monitor doesn't like (for those of us old enough to remember when we had to come up with modelines that suited our monitors and video cards before we could run X), and so the monitor is protecting itself by going into powersave mode. It's a flatscreen non-CRT monitor, so I don't even know if monitors still do that any more, but that's what it seems like.
If anyone knows what's happening, I'd very much appreciate hearing about it.