I find Firefox to be just a bit buggy. 1.0.2 and 1.0.3 ran ok for me in Fedora but not FreeBSD. 1.0.4 is crash prone I think. I have had Firefox crash a lot on some machines. I stopped using it in FreeBSD and run Mozilla instead. I haven't tried 1.0.6.
Also blocking pop ups seemed to make Firefox crash on some machines. Removing that from the preferences made it run more stable.
You mught try nuking Firefox off of your box, getting the latest .rpm from Mozilla and re-installing.
You might go to Mozilla's Get Firefox site for the binaries and compile from source.
http://www.mozilla.org/products/firefox/
One of those packages at least has an installer script with it.
Firefox is a good fast browser with lots of usefull plugins, just isn't quite solid yet.