Error in update checksum for x86_64

[Robert R. Kerr]

I am running fedora core 4 on an AMD x86_64 system.
Until today, yum update has worked fine.
However, now there seems to be an error in the checksum value posted 
with the most recent updates for the primary list:

When, as root, I type "yum update"
I get the following:

.....long list of attempts to read from many different mirrors, all 
failing as below...

Trying other mirror.
primary.xml.gz            100% |=========================| 344 kB    00:04
http://less.cogeco.net/pub/fedora/linux/core/updates/4/x86_64/repodata/primary.xml.gz: 
[Errno -1] Metadata file does not match checksum
Trying other mirror.
Error: failure: repodata/primary.xml.gz from updates-released: [Errno 
256] No more mirrors to try.

Any ideas?