[root@as yum.repos.d]# yum
There was a problem importing one of the Python modules
required to run yum. The error leading to this problem was:

   No module named yum

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:
2.4.2 (#1, Sep 28 2005, 10:25:47)
[GCC 3.4.3 20041212 (Red Hat 3.4.3-9.EL4)]

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