I had a similar problem with "stable" versions of Flash installed. Firefox wasn't crashing in my case it just seemed to sit there when I tried to view a Flash video, until I realized FF was refusing to run the flashplayer because it was outdated and insecure. I got fed up with that behavior and after searching around for a while I found Adobe's Labs (http://labs.adobe.com/) which is where they keep the Beta versions of flashplayer etc. Since installing and keeping updated with their Beta version I have only had one or two problems with it (touch wood). If you read the instructions you shouldn't go far wrong with it. Just remember to uninstall all previous versions with the uninstaller Adobe provide on the same "labs" paragraph as the (at present version 17.0.0.99) flashplayer. One benefit the Beta does provide is they don't try to sneak a toolbar through the back door as the aforementioned "stable" version.