general advice for rolling back yum updates?

[Mark Andrew Miller]

Hello, all.

I recently ran a <yum update> on my mythdora server, which updated my myth
applications from 0.22-1 to 0.22-5.  Now the mythfrontend application
terminates right after being launched and the log ends with


2010-02-28 10:27:10.774 Registering Internal as a media playback plugin.
Floating point exception

I have written to the myth users list, but I thought somebody on this list
might be able to give me some advice, too.

Since the previous version of the myth apps ran pretty well for me, I would
like explore the possibility of going back to that version.  However, I
don't have any experience rolling back yum updates  If rollbacks require
some before-the-fact configuration, I probably don't have that :-( 

Any suggestions?
Mark