Everyone should have the latest version of their preferred browser. And as they are free, why put up with an old version? I thought you had a recent version of Firefox AOG?
In the top bar, where it says Firefox, click on the drop down menu where it says About Firefox. If it is newer than 3.5 you are OK.
It looks to me as if this just means you need to be more astute in keeping your chosen browser up to date. This is easy:
(On the top toolbar) Help->Check For Updates (then follow the prompts).