By starting with a new profile, you can introduce your addons one at a time and if it is an addon, you'll know quickly. If it was a corrupted profile, then you have a clean start. With Windows 8 being new, there isn't a lot of experience with Firefox running on it. However, I read the mozilla support news groups each day and haven't seen any reports of problems with Windows 8.
Firefox updates are mostly about security fixes, and some improvements to the user interface. Of course, not everyone agrees about the latter

But the former are important. If you want a really stable version, get the Extended Support Release version, currently at 17.0.2 I think, as it only gets updated once a year other than security fixes.
Nothing wrong with Chrome either, I use it as a secondary browser.