Been getting this for the past few days:

/etc/cron.daily/yum:

Not using downloaded repomd.xml because it is older than what we have: Current : Fri Feb 26 18:03:06 2010 Downloaded: Thu Nov 5 20:40:44 2009

Then I ran yum clean all ; yum -d0 check-update and got

ftp://ftp.free.fr/mirrors/ftp.centos.org/5.4/extras/i386/repodata/primary.xml.gz: [Errno -1] Metadata file does not match checksum Trying other mirror. http://centos.mirror.connexeon.net/5.4/extras/i386/repodata/primary.xml.gz: [Errno -1] Metadata file does not match checksum Trying other mirror. http://centos.mirrors.skynet.be/pub/centos/5.4/extras/i386/repodata/primary....: [Errno -1] Metadata file does not match checksum Trying other mirror. [repeat]

Looks like there's a problem with the extras repo.

# find /var/cache/yum -name *.xml|xargs ls -l -rw-r--r-- 1 root root 951 Oct 19 21:25 /var/cache/yum/addons/repomd.xml -rw-r--r-- 1 root root 2142 Oct 2 13:31 /var/cache/yum/base/repomd.xml -rw-r--r-- 1 root root 1144 Nov 5 20:40 /var/cache/yum/extras/repomd.xml -rw-r--r-- 1 root root 1095 Sep 28 05:17 /var/cache/yum/rpmforge/repomd.xml