[CentOS] yum update fails for 5.6

google for "centos error performing checksum" refers to createrepo but of 
course "yum install createrepo" also fails and the instructions appear to be 
overkill.  Is there a "simple" soultion?

here's the result of yum update:

# yum -v update
Loading "fastestmirror" plugin
Config time: 0.118
Yum Version: 3.2.22
Setting up Package Sacks
Loading mirror speeds from cached hostfile
 * base: mirror.science.uottawa.ca
 * extras: mirror.science.uottawa.ca
 * rpmforge: ftp-stud.fht-esslingen.de
 * updates: mirror.science.uottawa.ca
rhel-src/primary                                                                                      | 
1.1 MB     00:02
ftp://ftp.redhat.com/pub/redhat/linux/enterprise/5Server/en/os/SRPMS/repodata/primary.xml.gz: 
[Errno -3] Error performing checksum
Trying other mirror.
Error: failure: repodata/primary.xml.gz from rhel-src: [Errno 256] No more 
mirrors to try.

and for repolist

# yum repolist
Loaded plugins: fastestmirror
Loading mirror speeds from cached hostfile
 * base: mirror.science.uottawa.ca
 * extras: mirror.science.uottawa.ca
 * rpmforge: ftp-stud.fht-esslingen.de
 * updates: mirror.science.uottawa.ca
rhel-src/primary                                                                                      | 
1.1 MB     00:02
ftp://ftp.redhat.com/pub/redhat/linux/enterprise/5Server/en/os/SRPMS/repodata/primary.xml.gz: 
[Errno -3] Error performing checksum
Trying other mirror.
Error: failure: repodata/primary.xml.gz from rhel-src: [Errno 256] No more 
mirrors to try.

TIA

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