compiz assert failure: compiz: /usr/include/boost/smart_ptr/shared_ptr.hpp:418: T* boost::shared_ptr<T>::operator->() const [with T = UnityFBO]: Assertion `px != 0' failed.

[Steve Magoun]

I encountered this crash after a reboot. Here's what I did:

1) Boot laptop, login to desktop
2) Attach external monitor
3) Launch nvidia-settings, detect displays, set external monitor to 'Twinview' mode. Notice bad display corruption for ~10sec on both screens.
4) Display corruption goes away; see external monitor is dark. Try to move nvidia-settings window to the second monitor, it doesn't work - Unity tries to pin it to the right half of my primary monitor.
5) The compiz-has-crashed dialog appeared here.

ProblemType: Crash
DistroRelease: Ubuntu 11.10
Package: unity 4.14.2-0ubuntu2
ProcVersionSignature: Ubuntu 3.0.0-11.17-generic 3.0.4
Uname: Linux 3.0.0-11-generic x86_64
NonfreeKernelModules: nvidia
ApportVersion: 1.22.1-0ubuntu2
Architecture: amd64
AssertionMessage: compiz: /usr/include/boost/smart_ptr/shared_ptr.hpp:418: T* boost::shared_ptr<T>::operator->() const [with T = UnityFBO]: Assertion `px != 0' failed.
CrashCounter: 1
Date: Mon Sep 12 09:42:58 2011
ExecutablePath: /usr/bin/compiz
InstallationMedia: Ubuntu 10.10 "Maverick Meerkat" - Beta amd64 (20100901.1)
ProcCmdline: compiz
ProcEnviron:
 PATH=(custom, user)
 LANG=en_US.UTF-8
 SHELL=/bin/bash
Signal: 6
SourcePackage: unity
StacktraceTop:
 raise () from /lib/x86_64-linux-gnu/libc.so.6
 abort () from /lib/x86_64-linux-gnu/libc.so.6
 __assert_fail () from /lib/x86_64-linux-gnu/libc.so.6
 UnityScreen::glPaintOutput(GLScreenPaintAttrib const&, GLMatrix const&, CompRegion const&, CompOutput*, unsigned int) () from /usr/lib/compiz/libunityshell.so
 GLScreen::glPaintOutput(GLScreenPaintAttrib const&, GLMatrix const&, CompRegion const&, CompOutput*, unsigned int) () from /usr/lib/compiz/libopengl.so
Title: compiz assert failure: compiz: /usr/include/boost/smart_ptr/shared_ptr.hpp:418: T* boost::shared_ptr<T>::operator->() const [with T = UnityFBO]: Assertion `px != 0' failed.
UpgradeStatus: Upgraded to oneiric on 2011-09-02 (9 days ago)
UserGroups: adm admin cdrom dialout lpadmin plugdev sambashare

[Apport retracing service (apport)]

Thank you for taking the time to report this crash and helping to make Ubuntu better. This particular crash has already been reported and is a duplicate of bug #838128, so is being marked as such. Please look at the other bug report to see if there is any missing information that you can provide, or to see if there is a workaround for the bug. Additionally, any further discussion regarding the bug should occur in the other report. Please continue to report any other bugs you may find.