compiz crashed with SIGSEGV in PrivateWindow::addWindowStackChanges()

No idea what happened.

ProblemType: Crash
DistroRelease: Ubuntu 11.10
Package: unity 4.18.0-0ubuntu1
ProcVersionSignature: Ubuntu 3.0.0-12.19-generic 3.0.4
Uname: Linux 3.0.0-12-generic x86_64
ApportVersion: 1.23-0ubuntu2
Architecture: amd64
CrashCounter: 1
Date: Thu Sep 29 08:55:17 2011
ExecutablePath: /usr/bin/compiz
InstallationMedia: Ubuntu 11.10 "Oneiric Ocelot" - Alpha amd64 (20110817)
ProcCmdline: compiz
ProcEnviron:
 PATH=(custom, user)
 LANG=de_DE.UTF-8
 SHELL=/bin/bash
SegvAnalysis:
 Segfault happened at: 0x43f766 <_ZN13PrivateWindow21addWindowStackChangesEP14XWindowChangesP10CompWindow+38>: mov 0x68(%rdx),%rdi
 PC (0x0043f766) ok
 source "0x68(%rdx)" (0x00000068) not located in a known VMA region (needed readable region)!
 destination "%rdi" ok
SegvReason: reading NULL VMA
Signal: 11
SourcePackage: unity
StacktraceTop:
 PrivateWindow::addWindowStackChanges(XWindowChanges*, CompWindow*) ()
 CompWindow::raise() ()
 CompScreen::handleEvent(_XEvent*) ()
 PrivateCompositeScreen::handleEvent(_XEvent*) () from /usr/lib/compiz/libcomposite.so
 CompScreen::handleEvent(_XEvent*) ()
Title: compiz crashed with SIGSEGV in PrivateWindow::addWindowStackChanges()
UpgradeStatus: No upgrade log present (probably fresh install)
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