Machine will not shut down.

[Aaron Konstam]

After I installed FC6 on one of my machines, shutdown no longer works. I
get the usual messages which would indicate the machine is shutting down
but the machine  in the end it sits there with the power still on. The
shutdown worked in all previous Linux versions but now it does not.

Where do I look for the problem? 
-- 
Aaron Konstam <akonstam at sbcglobal.net>