Orck. Firefox has always been a bugger to me because it is liable to all kinds of rules and direction,s from outside software.
I use it, I enjoy it, but I don't trust it. Although I trust it a lot more that Google Chrome, especially if you are into personal security.
My version is 29.01, probably the newest at this time…... That could change tomorrow very easily.
Advice,
Take it for what you paid for it.
Use a good A/V program. Nortons and McAfee's suck big maroon weenies. I use AVG or AVAST on my personal computers, allow it to update anytime it wants to.
Commercial systems get a different treatment I won't get into here.
D/L and use C Cleanup. Start out fixing anything more than the registry.
If that doesn't help, allow C Cleanera bit more access until you fix something that does work.
I have been working on computers for decades, THe first question they always ask is, "What's wrong with it?"
The next question is, "Can you fix it?"
The one after that is, "How did you fix it?"
Most of the time we have no idea how we did it so we make up a story on the fly for the rubes, or we have one already scripted!