[root@localhost ~]# yum update
Setting up Update Process
Setting up repositories
//var/cache/yum/core/repomd.xml:1: parser error : Document is empty

^
//var/cache/yum/core/repomd.xml:1: parser error : Start tag expected, '<' not found

^
core                      100% |=========================|    0 B    00:00
http://ayo.freshrpms.net/fedora/linux/4/x86_64/core/repodata/repomd.xml: [Errno -1] Error importing repomd.xml for core: Error: could not parse file //var/cache/yum/core/repomd.xml
Trying other mirror.
Cannot open/read repomd.xml file for repository: core
failure: repodata/repomd.xml from core: [Errno 256] No more mirrors to try.
Error: failure: repodata/repomd.xml from core: [Errno 256] No more mirrors to try.