I have used Firefox for several years now and have had no problems whatsoever with it.
I would uninstall it. Run SpyBot, CCleaner, Ad-Aware, and an anti-viral program. Then run a Defrag program. I like Defraggler (another free download), but the MS one should be OK.
Now, download it. Don't get any add-ons and so forth. I have done this, and again, I have had no problems with the add-ons.
You should be good to go.
The king is not dead, unfortunately. Long live Firefox!
JayR