Totem can't read DVD (resindvdsrc.c error)

Binary package hint: totem

Trying to open an encrypted DVD, with libdvdcss2 installed from Medibuntu repositories, Totem displays "An error ocurred. Couldn't open location ; maybe you don't have permission to open the file."

This is terminal output :

steph@steph-desktop:~$ totem
/var/lib/python-support/python2.6/gdata/tlslite/utils/cryptomath.py:9: DeprecationWarning: the sha module is deprecated; use the hashlib module instead
  import sha
** Message: no file info
libdvdread: Using libdvdcss version 1.2.10 for DVD access
libdvdread: Invalid IFO for title 1 (VTS_01_0.IFO).
libdvdread: Using libdvdcss version 1.2.10 for DVD access
libdvdread: Invalid IFO for title 1 (VTS_01_0.IFO).
** Message: Error: Impossible de lire les informations de titre du DVD.
resindvdsrc.c(333): rsn_dvdsrc_start (): /GstPlayBin:play/RsnDvdBin:source/resinDvdSrc:dvdsrc:
system error: Erreur d'entrée/sortie

ProblemType: Bug
Architecture: i386
DistroRelease: Ubuntu 9.04
ExecutablePath: /usr/bin/totem-gstreamer
Package: totem-gstreamer 2.26.1-0ubuntu5
ProcEnviron:
 SHELL=/bin/bash
 LANG=fr_FR.UTF-8
SourcePackage: totem
Uname: Linux 2.6.28-11-generic i686