What parts of your computer should an antivirus program protect?

McAfee is pure garbage.   The worst out there.  Even McAfee himself said it was garbage and shouldn't use it. It's a giant resource/memory hog and has terrible detection rates. It's almost worse than nothing at all since it provides a sense of security when there isn't really much of one and is mostly just bloat on your machine.

Ideally an antivirus service should cover all aspects of a machine and include adware, trojans, hijacks, and spyware.   Many however say those forms of maleware aren't true viruses.

She's giving you a garbage explanation because a) she doesn't know what she is talking about or b) she is paid to convince you that you aren't covered & you must spend more money to get help.  

Yes, you have been infected with malware (yes, a virus) that is hijacking your browsers and there may be something more that it is doing to your hard drive that you haven't detected yet.  Yes, I believe they should be covering this free of charge.  But, what you and I think doesn't matter. They don't think it's their responsibility.

Do you have a local computer guy/techie that you buy your computer(s) from or bring your computer to when it crashes or there are problems?  If so, call him.  If not, find one.  He/she will get your problem resolved quickly. Of course, it will cost you something for his time (probably an hour's labor) but it won't be any more than what McAfee will try to squeeze you for. And, more importantly, how much is YOUR time worth?  He/she more than likely has dealt with the virus and has the patch to fix it, whereas you will be spending hours on the phone with McAfee trying to find someone who can help you without any guarantee they will fix it.  

It's worth the investment to avoid the headaches.  Also, your time is better spent elsewhere.   

You're probably gonna have to do a clean install of your OS.. that would be the best option for you at this point. an AV should protect the whole of the operating system but it fails sometimes.. but don't go with norton or mcafee next time because they are the worst products on the market (both are absolute junk in every way and not worth a penny).. This post was edited by Skunky Stinkerson at February 7, 2017 1:31 PM MST

You obviously have picked up malware in the form of spyware or a trojan somewhere that McAfee can't detect because it's stuck in there real good, it sounds like. Best thing to try next is to go Skunky's route and then install Webroot and rid yourself of that clunker AV that you have.
Second choice is to let those people I told you about, go through it and clean it out but you don't want to spend the money and a Tech will charge you even more.
Third choice is to go look at a decent ASUS Laptop and start fresh. Data transfer is easy also. I would call a couple of PC repair shops and check with them for a clean unit. That way you won't get all the junk like you would with one bought from a store.
Something to think about as it looks like that's your only option.
A decent AV should protect you from 99% of the junk that tries to come through. Malwarebytes will get anything else. This post was edited by Benedict Arnold at February 7, 2017 1:31 PM MST

There are free Antivirus apps you can download then burn on to a cd... you then turn off the computer and then reboot it from the cd ... all major  AV manufacturers supply them on their Web sites ... the advantage  of this approach is the virus can't start and protect itself when Windows starts because you are booting from the cd ... and that's often a linux operating system... the cd will scan your computer and the virus won't be active so it can't protect itself ... try this approach first .. it's free and effective ... good luck This post was edited by Benedict Arnold at February 7, 2017 1:32 PM MST

it should be protecting all of it

all software parts including your browser. Did you consider changing your anti virus service provider?