compiz crashed with SIGSEGV in pthread_mutex_lock()

[Gianluca Mattiuzzi]

Binary package hint: compiz

When logging in, Unity doesn't start and I using gnome-panel.
After gnome-panel startup sometime a compiz error occurred.

ProblemType: Crash
DistroRelease: Ubuntu 11.04
Package: compiz-core 1:0.9.4-0ubuntu1
ProcVersionSignature: Ubuntu 2.6.38-5.32-generic 2.6.38-rc6
Uname: Linux 2.6.38-5-generic i686
Architecture: i386
CrashCounter: 1
Date: Sat Feb 26 13:20:13 2011
ExecutablePath: /usr/bin/compiz
InstallationMedia: Ubuntu 10.04 "Lucid Lynx" - Beta i386 (20100318)
ProcCmdline: compiz
ProcEnviron:
 LANGUAGE=it_IT:en
 LANG=it_IT.UTF-8
 SHELL=/bin/bash
SegvAnalysis:
 Segfault happened at: 0xd6033d <pthread_mutex_lock+29>: mov 0xc(%esi),%edi
 PC (0x00d6033d) ok
 source "0xc(%esi)" (0x632f6582) not located in a known VMA region (needed readable region)!
 destination "%edi" ok
SegvReason: reading unknown VMA
Signal: 11
SourcePackage: compiz
StacktraceTop:
 pthread_mutex_lock () from /lib/libpthread.so.0
 ?? () from /lib/libglib-2.0.so.0
 Glib::Source::unreference() const () from /usr/lib/libglibmm-2.4.so.1
 PrivateScreen::~PrivateScreen() ()
 PrivateScreen::~PrivateScreen() ()
Title: compiz crashed with SIGSEGV in pthread_mutex_lock()
UserGroups: adm admin audio cdrom dialout dip fax floppy fuse lpadmin netdev plugdev sambashare tape video

[Apport retracing service (apport)]

StacktraceTop:
 pthread_mutex_lock () from /lib/libpthread.so.0
 g_source_unref_internal () from /lib/libglib-2.0.so.0
 Glib::Source::unreference() const () from /usr/lib/libglibmm-2.4.so.1
 ~RefPtr (this=0x8f07540, __in_chrg=<value optimized out>) at /usr/include/glibmm-2.4/glibmm/refptr.h:207
 PrivateScreen::~PrivateScreen (this=0x8f07540, __in_chrg=<value optimized out>) at /build/buildd/compiz-0.9.4/src/screen.cpp:4776