Comment 7 for bug 559056

Okay, I learned much more. compizconfig-settings-manager was not installed. The upgrade defaulted to installing compiz, but without the necessary utilities.

So I see several bugs here:
1.)
The video was basically destroyed after the upgrade. I kept getting error messages about missing drivers
or non-existent drivers, and then the screen would go black, and the system was useless.
It was necessary to do a modeswitch setting to even get the windowing system to work at all:
(this was done by booting into the previous kernel. Hold down shift key while booting. Tapping it does not work.
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echo options i915 modeset=1 | sudo tee /etc/modprobe.d/i915-kms.conf
sudo update-initramfs -u
---------------

2.)
previous garbage caused misfonfiguration of the video system. It was necessary to purge and
reinstall things. Run, as root, this script:
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#!/bin/bash
apt-get purge nvidia*
apt-get install --reinstall xserver-xorg-video-intel libgl1-mesa-glx libgl1-mesa-dri xserver-xorg-core
dpkg-reconfigure xserver-xorg
update-alternatives --remove gl_conf /usr/lib/nvidia-current/ld.so.conf
-----------------

3.)
Install compizconfig-settings-manager. I used dselect, and chose every compiz thing that looked
relevant. I suppose apt-get would also work.

4.) Trying to change number of workspaces by right-clicking the workspace array in the lower right-hand corner and trying to change preferences produced disastrous results.
I haven't tried it again now, after installing compizconfig-settings-manager. I have a working system
at the moment, and am not eager to destroy it again today.
Maybe next month.

Have a good day.