yum trouble

[hicham]

 Hello
  each time I do a yum update ,I keep having those outputs:
 Trying other mirror.
 primary.xml.gz            100% |=========================| 433 kB    00:15
 http://mirrors.kernel.org/fedora/core/updates/5/x86_64/repodata/primary.xml.gz:
 [Errno -1] Metadata file does not match checksum
 Trying other mirror.
 primary.xml.gz            100% |=========================| 433 kB    00:14
 http://ftp.upjs.sk/pub/fedora/linux/core/updates/5/x86_64/repodata/primary.xml.gz:
 [Errno -1] Metadata file does not match checksum
 Trying other mirror.
 primary.xml.gz            100% |=========================| 433 kB    00:14
 http://ftp1.skynet.cz/pub/linux/fedora/updates/5/x86_64/repodata/primary.xml.gz:
 [Errno -1] Metadata file does not match checksum
 Trying other mirror.

 anyone got a solution for this ?
 thanks
 hicham