latest yum fails

[Nave, Ronald]

I have installed  yum-2.1.8-1 and get the following error message

Traceback ( most recent call last)
File "/usr/bin/yum" line 6 
import yummain
InportError: No module named yummain


Yum has been broken for several weeks.

The latest update does not seem to improve things.

Up2date works , but only if I update one or two files at a time.

If I attempt to "update everything" it ususally locks up.