changing compiz setting breaks Unity desktop

[Andy Stanford-Clark]

similar to https://bugs.launchpad.net/ubuntu/+source/compizconfig-settings-manager/+bug/773958 but more severe!

I tried to change a setting on Compiz. I can't remember which one it was, but I think it was one of the Window Management ones.
It asked me something about turning on OpenGL, then it asked something about Mouse Position Polling, both of which I said yes to.

Then Compiz crashed with an error (and sent off a report).
Then Unity sort of crashed and came back with just a desktop - background with document icons... but no left-hand launcher or the top bar (where the clock and battery, etc, indicators are).

Logging out didn't help, rebooting didn't help - Unity just came back with no launcher or top bar.

Selecting unity 2D from the login screen *did* work, so I was able to research possible fixes.

Eventually I fixed it by some combination of:
uninstall compizconfig-settings-manager
rm -r ~/.compiz-1
   (that might be a red herring, as I notice it hasn't recreated that now I've reinstalled compizconfig!)
get an Xterm up in the launcher-less Unity (login to a console, export DISPLAY=:0, xterm, ctrl-alt-f7)
in the xterm run unity --reset
The launcher reappears... but unity --reset hangs, and when I ctrl-C it, the launcher disappears when the app exits.
Tried unity --reset-icons
that runs to completion, but no launcher
ran unity --reset again
launcher came back, command hung, but launcher remained when I ctrl-C'd it.
reboot
all working fine.
Phew!

Moral of the story? Don't play with compiz settings!

ProblemType: Bug
DistroRelease: Ubuntu 12.04
Package: compizconfig-settings-manager 0.9.5.92-0ubuntu3
ProcVersionSignature: Ubuntu 3.2.0-38.61-generic 3.2.37
Uname: Linux 3.2.0-38-generic x86_64
NonfreeKernelModules: symap_custom_3.2.0_38_generic_x86_64 symev_custom_3.2.0_38_generic_x86_64
ApportVersion: 2.0.1-0ubuntu17.1
Architecture: amd64
Date: Tue Mar 5 15:25:09 2013
InstallationMedia: Ubuntu 12.04.1 LTS "Precise Pangolin" - Release amd64 (20120823.1)
MarkForUpload: True
PackageArchitecture: all
ProcEnviron:
 LANGUAGE=en_GB:en
 TERM=xterm
 PATH=(custom, no user)
 LANG=en_GB.UTF-8
 SHELL=/bin/bash
SourcePackage: compizconfig-settings-manager
UpgradeStatus: No upgrade log present (probably fresh install)

[Phillip Susi (psusi)]

This package has been removed from Ubuntu. Closing all related bugs.