missing repo, no repomd, no metalink.xml

[Shane]

Hi,

   I'm using Fedora18 x86_64.  (Yes, it's old.)  Within the last few 
days I found that I cannot install or list anything from the fedora-18 
repo via yum. I get the typical errors everybody complains about "no 
repomd" and "metalink.xml does not exist".  Common workarounds from 
google searches haven't worked.

   I opened the link spit out by yum 
"http://mirrors.fedoraproject.org/metalink?repo=fedora-18&arch=x86_64" 
in a browser.  It downloaded a metalink file (no .xml suffix).  The 3rd 
(or so) line of the file has the following dubious message.

# repo = fedora-18 arch = x86_64 error: invalid repo or arch

   Following this line is a HUGE listing of available repos and 
architectures.  There is nothing shown for fedora-18 arch i386 or 
x86_64.  In fact, even fedora-source-18 repo is missing.  I don't think 
this is a yum problem on my system.

   Is there something else I can try (yum-wise)?  If I need to report it 
then where?  I'm quite certain that this is the wrong list.

   Thanks.

   Shane