Erreur de transaction sous fedora 11

Bonjour,

j'ai installé il y a 3 jours fedora 11 et lorsque j'essai d'installer un logiciel ou une mise a jour, un message d'erreur s'affiche: erreur de transaction

ERREUR de résolution de dépendance par rpm_check_debug :
rpmlib(PayloadIsXz) is needed by dejavu-fonts-common-2.30-2.fc12.noarch
rpmlib(PayloadIsXz) is needed by lohit-gujarati-fonts-2.4.3-1.fc12.noarch
rpmlib(PayloadIsXz) is needed by subversion-1.6.5-1.fc12.x86_64
rpmlib(PayloadIsXz) is needed by ncurses-base-5.7-3.20090207.fc12.x86_64
rpmlib(PayloadIsXz) is needed by libXfixes-4.0.3-8.fc12.x86_64
rpmlib(PayloadIsXz) is needed by pygobject2-2.18.0-2.fc12.x86_64
rpmlib(PayloadIsXz) is needed by libblkid-2.16-8.fc12.x86_64
rpmlib(PayloadIsXz) is needed by rpm-4.7.1-4.fc12.x86_64
rpmlib(PayloadIsXz) is needed by bcm43xx-fwcutter-006-6.fc12.x86_64
rpmlib(PayloadIsXz) is needed by xorg-x11-xtrans-devel-1.2.2-4.fc12.noarch
rpmlib(PayloadIsXz) is needed by libXdmcp-1.0.2-11.fc12.x86_64
rpmlib(PayloadIsXz) is needed by lohit-tamil-fonts-2.4.3-1.fc12.noarch
rpmlib(PayloadIsXz) is needed by xorg-x11-drv-sisusb-0.9.3-1.fc12.x86_64
rpmlib(PayloadIsXz) is needed by libtasn1-devel-2.3-1.fc12.x86_64
rpmlib(PayloadIsXz) is...

et la fenetre d'installation reste bloqué au stade d' "essai des changements"
voilà mon problème et merci d'avance pour votre aide