Bankerfox - that is the clue to your problems. There is no such thing its a fake report by some malware running on your computer, which is probably also responsible for the random changes to firefox.

malwarebytes from http://malwarebytes.org will most likely fix the problem but you may need to get rid of the proxy setting the malware has installed in IE and Firefox.

You will need advice of exactly how to run malwarebytes so that the malware doesn't disable it.

If you have used any sensitive sites such as banking since you first noticed problems you need to log on to them from another computer ASAP and change your password, passwords typed on your computer may have been collected.

Sorry to bring you bad news.

Advice to everyone is, if you get virus/malware warnings in a format your don't recognise from a program you didn't install then it isn't genuine; especially if it offers to fix the problem if you pay for some software.

Simon