To clear the cache, go to your Tools menu, Options. A new tab will appear, on the left pane select Advanced. On the right at the top is a series of tabs (not webpage tabs, below that), General, Data Choices, etc. Select Network. In the middle is Cached Web Content, and there's a button on the far right, Clear Now - click it. That's all. No it won't clear your passwords.
Also in the Tools menu is Add-ons. Depending on how McAfee installed itself, you may have an extension or a plug-in (on the left pane again) labeled McAfee... I would try to disable it temporarily, just to see if it fixes the problem.
Another thing to try, that I don't know how to do, is to check McAfee for virus definitions updates. My thinking is it should do this automatically, but it never hurts to force it.
That's as easy as clicking this link and saving the download somewhere you'll find it, then go to it and double-click to install. https://www.mozilla.org/en-US/firefox/new/?scene=2
Okay I have reinstalled firefox. The "Advanced" button as recommended to use in your easy to follow instructions still does not work. I still cannot get into catcentric
I looked at the "add-on" from your instructions. Mcafee is listed on the plug ins page but there isn't any option to disable it.
However, since I can get into catcentric on IE, it has to be a firefox thing, right? So why can't I get into that Advanced option?.
Wait...do I have to reboot before the new firefox is working? Let's see