gnome-shell crashed with SIGSEGV in meta_workspace_list_windows()

[sergio]

just crashed, I was using Firefox 25.0.1, Spotify 0.9.4.183..., JDownloader 0.9.581, Liferea 1.8.15, File (nautilus) 3.10.1, Cairo-Dock

ProblemType: Crash
DistroRelease: Ubuntu 13.10
Package: gnome-shell 3.10.2.1-0ubuntu1~saucy1 [origin: LP-PPA-gnome3-team-gnome3-staging]
ProcVersionSignature: Ubuntu 3.11.0-13.20-generic 3.11.6
Uname: Linux 3.11.0-13-generic i686
ApportVersion: 2.12.5-0ubuntu2.1
Architecture: i386
CrashCounter: 1
Date: Sat Nov 30 18:39:24 2013
DisplayManager: gdm
ExecutablePath: /usr/bin/gnome-shell
InstallationDate: Installed on 2013-10-19 (42 days ago)
InstallationMedia: Ubuntu-GNOME 13.10 "Saucy Salamander" - Release i386 (20131017)
MarkForUpload: True
ProcCmdline: /usr/bin/gnome-shell
ProcEnviron:
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=it_IT.UTF-8
 SHELL=/bin/bash
SegvAnalysis:
 Segfault happened at: 0xb72fc01e <meta_workspace_list_windows+30>: mov 0xc(%esi),%eax
 PC (0xb72fc01e) ok
 source "0xc(%esi)" (0x0000000c) not located in a known VMA region (needed readable region)!
 destination "%eax" ok
SegvReason: reading NULL VMA
Signal: 11
SourcePackage: gnome-shell
StacktraceTop:
 meta_workspace_list_windows () from /usr/lib/libmutter.so.0
 ?? () from /usr/lib/libmutter.so.0
 ?? () from /usr/lib/libmutter.so.0
 ?? () from /usr/lib/libmutter.so.0
 ?? () from /usr/lib/i386-linux-gnu/libclutter-1.0.so.0
Title: gnome-shell crashed with SIGSEGV in meta_workspace_list_windows()
UpgradeStatus: No upgrade log present (probably fresh install)
UserGroups: adm cdrom dip libvirtd lpadmin plugdev sambashare sudo

[Ubuntu GNOME (ug-bot)]

StacktraceTop:
 meta_workspace_list_windows (workspace=0x0) at core/workspace.c:745
 window_would_be_covered (newbie=0x8d87988) at core/window.c:2816
 meta_window_show (window=0x8d87988) at core/window.c:3000
 implement_showing (window=0x8d87988, showing=showing@entry=1) at core/window.c:2259
 idle_calc_showing (data=0x0) at core/window.c:2371