yum confused?

If you run a 'yum upgrade' and end up with a message like this:

Error: failed to retrieve repodata/filelists.xml.gz from rhel-x86_64-server-5 
error was [Errno -1] Metadata file does not match checksum 
 You could try using --skip-broken to work around the problem 
 You could try running: package-cleanup --problems 
                        package-cleanup --dupes 
                        rpm -Va --nofiles --nodigest 

it's likely that yum got confused. This happened to me when I changed a subscription channel, re-registered a system and tried to yum upgrade. I have been able to consistently fix it by running:

 rm -rf /var/cache/yum/*
 yum clean all
 yum update