fedora and firefox ... what am I doing wrong?

[Skunk Worx]

I am using FC5 and firefox. I keep it yum updated.

Something has gone awful on this machine, not sure how to fix it.

Suppose I go to npr.org, then search for linux related stories.

Now I click on one in the return list, say :

http://www.npr.org/templates/story/story.php?storyId=5289411

There is a SMIL link at the top. Click it.

Now firefox-bin goes to 98-99 % cpu for almost 30 seconds. I guess it's 
just spinning CPU. The GUI doesn't refresh during this entire time and 
is unresponsive to mouse or keyboard. X still works; I can raise and 
lower other windows and use other applications.

This is happening on many links lately, not just NPR.

Has anyone else seen this problem?

---
John