[CentOS] Perl package problems

For a while now I've been seeing skipped-package notices, which I don't really 
understand.  I know it's a version mis-match, but all my attempts to sort it 
out have failed, so I need help, please.  The current state is

Skipping filters plugin, no data
--> Running transaction check
---> Package perl-Compress-Zlib.x86_64 0:2.020-119.el6 will be obsoleted
---> Package perl-IO-Compress.noarch 0:2.037-1.el6.rfx will be obsoleting
--> Processing Dependency: perl(Compress::Raw::Zlib) = 2.037 for package: 
perl-IO-Compress-2.037-1.el6.rfx.noarch
---> Package perl-IO-Compress-Base.x86_64 0:2.020-119.el6 will be obsoleted
---> Package perl-IO-Compress-Zlib.x86_64 0:2.020-119.el6 will be obsoleted
--> Finished Dependency Resolution

Packages skipped because of dependency problems:
    perl-IO-Compress-2.037-1.el6.rfx.noarch from rpmforge-extras

Can someone please tell me what needs erasing/installing/updating to get this 
cleaned up?

Thanks

Anne
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