Hello, I'm under Lucid, I don't know if it's a bug because there was this development repository:
deb http://ppa.launchpad.net/gstreamer-developers/ppa/ubuntu lucid main
installed that I forgot to uninstall. I've installed it because I was asking myself how does PPA works.

So maybe I had the latest before it arrived on " Sources de Logiciels " in french +- " Software Sources / Update Manager in english ", command line:
gksu --desktop /usr/share/applications/software-properties-gtk.desktop /usr/bin/software-properties-gtk ()

The error is as follows:
E: /var/cache/apt/archives/gstreamer0.10-plugins-bad_0.10.19-1~lucid1_i386.deb: tentative de remplacement de « /usr/lib/gstreamer-0.10/libgstvalve.so », qui appartient aussi au paquet gstreamer0.10-plugins-good 0

(translation: ... while trying to replace ... that also belongs to package ...)

System asked to report bug here, but I couldn't do it automatically, because Ubuntu Linux failed on self authentification.

Right now I can't know if this supposed bug has an effect in system. I don't know how to test it. So I put minor.