HomeDad- The add-ons are what makes FF such a great browser, don't bail out on them entirely. Try adding them back in one at a time and see how it goes. I had a similar problem and it turned out to be an image-zoom add-on. I found a different one and now everything's fine again.

I started out with nothing & I've still got most of it left
M60 VP160 QS8 EP350
M22 VP100
Algonquins