Firefox freezes when rendering dropdown window

I'm using Mac OS X 10.2.8 on a G4.

When I choose any button or text box that creates a dropdown window or
pulldown (like the triangle immediately to the right of the back arrow)
including those on some web pages Firefox will freeze indefinitely.

Force quit indicates Firfox is not responding and I always resort to force
quitting.  This happens ~80% of the time a drop window is rendered and is
very repeatable.

I have the default (2.0) Firefox theme.   The only extensions I have enabled
are Dom Inspector 1.8, Talkback 1.5, and Mimetype Editor 0.2

I've also tried starting Firefox up in safe mode from the command line and
still get it to hang.