error messages when upgrading with Update manager

every time i try to upgrade the linux ubuntu with the update manager, it gives me an error message "Package operation Failed : the installation or removal of a software package FAILED"
the softwares are installed but it always gives me this message.

ProblemType: Bug
DistroRelease: Ubuntu 11.04
Package: libgstreamer0.10-0 0.10.32-3ubuntu3
ProcVersionSignature: Ubuntu 2.6.38-10.46-generic 2.6.38.7
Uname: Linux 2.6.38-10-generic i686
NonfreeKernelModules: fglrx
Architecture: i386
Date: Sun Jul 3 13:39:44 2011
ExecutablePath: /usr/bin/totem
InstallationMedia: Ubuntu 10.04 LTS "Lucid Lynx" - Release i386 (20100429)
ProcEnviron:
 LANGUAGE=en_US:en
 LANG=en_US.UTF-8
 SHELL=/bin/bash
SourcePackage: gstreamer0.10
UpgradeStatus: Upgraded to natty on 2011-04-28 (65 days ago)
XsessionErrors:
 (gnome-settings-daemon:1337): GdkPixbuf-CRITICAL **: gdk_pixbuf_format_get_name: assertion `format != NULL' failed
 (gnome-settings-daemon:1337): GdkPixbuf-CRITICAL **: gdk_pixbuf_format_get_name: assertion `format != NULL' failed
 (gnome-settings-daemon:1337): GdkPixbuf-CRITICAL **: gdk_pixbuf_format_get_name: assertion `format != NULL' failed