had also problem with YUM becouse one of repositories was wrong.
solution was to build new ones su -
U can look at mine fine working repos
/etc/yum.repos.d/rpmfusion-free-updates-testing.repo
/etc/yum.repos.d/fedora-updates.repo
/etc/yum.repos.d/google.repo
/etc/yum.repos.d/rpmfusion-nonfree.repo
/etc/yum.repos.d/skype.repo
/etc/yum.repos.d/rpmfusion-free-updates.repo
/etc/yum.repos.d/rpmfusion-nonfree-rawhide.repo
/etc/yum.repos.d/fedora.repo
/etc/yum.repos.d/rpmfusion-free.repo
/etc/yum.repos.d/adobe-linux-i386.repo
/etc/yum.repos.d/rpmfusion-nonfree-updates-testing.repo
/etc/yum.repos.d/freshrpms.repo
/etc/yum.repos.d/fedora-rawhide.repo
/etc/yum.repos.d/rpmforge.repo
/etc/yum.repos.d/rpmfusion-free-rawhide.repo
/etc/yum.repos.d/fedora-updates-testing.repo
/etc/yum.repos.d/rpmfusion-nonfree-updates.repo
If .repos are OK make a backup of them and install new fresh YUM
U can follow this howtos
http://www.fdcservers.net/vbulletin/...php/t-376.html