firefox is not caching to disk (or memory probably either) for some reason (could be because in prefs.js there is no setting line -browser.disk.cache although it may be missing as default)
Is there some other place on disk where you can find text from page ffox displayed before it crashed?
Best bet is to uninstall it and set it up again with a new download. How to know you are getting old 2:
Your feet seem further away from your hands