nautilus crashed with SIGSEGV in g_type_check_instance_is_a()

Binary package hint: nautilus

from a terminal : sudo nautilus , after exiting from nautilus , got

"

Nautilus-Share-Message: Called "net usershare info" but it failed: « net usershare » a retourné l'erreur 255 : net usershare: cannot open usershare directory /var/lib/samba/usershares. Error No such file or directory
Please ask your system administrator to enable user sharing

"

ProblemType: Crash
Architecture: i386
CrashCounter: 1
Date: Thu Jul 30 11:25:10 2009
DistroRelease: Ubuntu 9.10
ExecutablePath: /usr/bin/nautilus
Package: nautilus 1:2.27.4-0ubuntu2 [modified: usr/bin/nautilus usr/bin/nautilus-file-management-properties usr/bin/nautilus-autorun-software usr/bin/nautilus-connect-server]
ProcCmdline: nautilus
ProcEnviron:
 PATH=(custom, no user)
 LANG=fr_FR.UTF-8
 SHELL=/bin/bash
ProcVersionSignature: Ubuntu 2.6.31-4.23-generic
SegvAnalysis:
 Segfault happened at: 0x46f5f1f3 <g_type_check_instance_is_a+83>: testb $0x40,0x7(%edi)
 PC (0x46f5f1f3) ok
 source "$0x40" ok
 destination "0x7(%edi)" (0x1015ff6b) not located in a known VMA region (needed writable region)!
SegvReason: writing unknown VMA
Signal: 11
SourcePackage: nautilus
StacktraceTop:
 g_type_check_instance_is_a ()
 g_object_unref () from /usr/lib/libgobject-2.0.so.0
 ?? ()
 g_object_unref () from /usr/lib/libgobject-2.0.so.0
 ?? ()
Title: nautilus crashed with SIGSEGV in g_type_check_instance_is_a()
Uname: Linux 2.6.31-4-generic i686
UserGroups: