Yum doesn't seem to work properly on F13

[eavatar]

Hey,

I am facing an unusual problem with my Fedora 13 install. I can't use yum and upgrade or install any package by this method. And for some unusual reason the system upgrade works properly, installing all the upgrades normally.

Everytime I try upgrade or install anything else by command line I get this error message

eavatar]# yum upgrade
Plugins carregados: fastestmirror, presto, protect-packages, protectbase,
                  : refresh-packagekit, remove-with-leaves, rpm-warm-cache
Loading mirror speeds from cached hostfile
fedora/metalink                                          | 1.8 kB     00:00     
 * fedora: mirrors.ucr.ac.cr
 * updates: mirror.pnl.gov
http://mirrors.ucr.ac.cr/fedora/releases/13/Everything/i386/os/repodata/repomd.xml: [Errno 14] HTTP Error 403 : http://mirrors.ucr.ac.cr/fedora/releases/13/Everything/i386/os/repodata/repomd.xml 
Tentando outro espelho.
http://fedora.c3sl.ufpr.br/linux/releases/13/Everything/i386/os/repodata/repomd.xml: [Errno 14] HTTP Error 403 : http://fedora.c3sl.ufpr.br/linux/releases/13/Everything/i386/os/repodata/repomd.xml 
Tentando outro espelho.
http://fedora.pop.com.br/linux/releases/13/Everything/i386/os/repodata/repomd.xml: [Errno 14] HTTP Error 403 : http://fedora.pop.com.br/linux/releases/13/Everything/i386/os/repodata/repomd.xml 
Tentando outro espelho.
http://mirror.ispbrasil.com.br/fedora/releases/13/Everything/i386/os/repodata/repomd.xml: [Errno 14] HTTP Error 403 : http://mirror.ispbrasil.com.br/fedora/releases/13/Everything/i386/os/repodata/repomd.xml 
Tentando outro espelho.
Error: Cannot retrieve repository metadata (repomd.xml) for repository: fedora. Please verify its path and try again

This problem is similar to the one faced on this topic http://forums.fedoraforum.org/showthread.php?t=245368 , but unfortunately it hadn't display any solution.

So doctors, my Yum has any chance to get healed?