There should not be a problem, considering worst case; let us suppose it isn't working. Why don't you go for latest Firefox version and Ubuntu 14.01/14.10? Current version of Firefox is 36.0.1, check what version you have. [IMP]Also check you Clock, sometimes due to security & privacy issues, browser blocks the websites which do not match time.
Well, Thats great @todd . Sorry, couldn't get to you in time. I would like to add that, make sure your Software updates are on, so that not only firefox, but also other softwares will get a stable release in every update.
Consider the foll. image,
Make sure you have Main,Universe and Multiverse checked at the minimum in Softwares & Updates. You can find that in your Applications menu.