Red Hat Enterprise Linux 5 で "No module named cElementTree" 問題が発生し yum コマンドが失敗する

Issue

• yum コマンドに失敗し、以下のメッセージが表示されます。

There was a problem importing one of the Python modules  
required to run yum.The error leading to this problem was:  

   No module named cElementTree  

Please install a package which provides this module, or  
verify that the module is installed correctly.  

It's possible that the above module doesn't match the  
current version of Python, which is:  
2.4.3 (#1, Jun 11 2009, 14:09:58)
[GCC 4.1.2 20080704 (Red Hat 4.1.2-44)]

If you cannot solve this problem yourself, please go to 
the yum faq at:  
  http://wiki.linux.duke.edu/YumFaq