compiz crashed with SIGSEGV in main_arena()

[dazza5000]

running latest packages on precise - this happens when I change my monitor configuration using the "displays" configuration window

ProblemType: Crash
DistroRelease: Ubuntu 12.04
Package: unity 5.4.0-0ubuntu2
ProcVersionSignature: Ubuntu 3.2.0-17.27-generic 3.2.6
Uname: Linux 3.2.0-17-generic x86_64
NonfreeKernelModules: fglrx
ApportVersion: 1.93-0ubuntu2
Architecture: amd64
CrashCounter: 1
Date: Sun Feb 26 23:56:12 2012
ExecutablePath: /usr/bin/compiz
InstallationMedia: Ubuntu 11.04 "Natty Narwhal" - Release amd64 (20110427.1)
ProcCmdline: compiz
ProcEnviron:
 LANGUAGE=en_US:en
 PATH=(custom, no user)
 LANG=en_US.UTF-8
 SHELL=/bin/bash
SegvAnalysis:
 Segfault happened at: 0x7f1eb6a46778: mov $0xb4,%al
 PC (0x7f1eb6a46778) in non-executable VMA region: 0x7f1eb6a46000-0x7f1eb6a48000 rw-p /lib/x86_64-linux-gnu/libc-2.15.so
 source "$0xb4" ok
 destination "%al" ok
SegvReason: executing writable VMA /lib/x86_64-linux-gnu/libc-2.15.so
Signal: 11
SourcePackage: unity
StacktraceTop:
 ?? () from /lib/x86_64-linux-gnu/libc.so.6
 unity::ui::PointerBarrierWrapper::EmitCurrentData() () from /usr/lib/compiz/libunityshell.so
 ?? () from /usr/lib/compiz/libunityshell.so
 ?? () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
 g_main_context_dispatch () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
Title: compiz crashed with SIGSEGV in unity::ui::PointerBarrierWrapper::EmitCurrentData()
UpgradeStatus: Upgraded to precise on 2011-09-23 (156 days ago)
UserGroups: adm admin cdrom dialout lp lpadmin plugdev root sambashare vboxusers

[Apport retracing service (apport)]

StacktraceTop:
 main_arena () from /tmp/tmpxMHgLq/lib/x86_64-linux-gnu/libc.so.6
 emit (_A_a2=..., _A_a1=@0x7fffceb4aeb8, impl=<optimized out>) at /usr/include/sigc++-2.0/sigc++/signal.h:1252
 emit (_A_a2=..., _A_a1=@0x7fffceb4aeb8, this=<optimized out>) at /usr/include/sigc++-2.0/sigc++/signal.h:2891
 unity::ui::PointerBarrierWrapper::EmitCurrentData (this=0x410fe00) at /build/buildd/unity-5.4.0/plugins/unityshell/src/PointerBarrier.cpp:121
 operator() (user_data=0x410fe00, this=<optimized out>) at /build/buildd/unity-5.4.0/plugins/unityshell/src/PointerBarrier.cpp:146