Browser extensions may hijack your browser. The best approach is to have NONE of these on your computer. Getting rid of them, once they are on your computer, can be problematic.
I wrote before about ASK (formerly ASK JEEVES) and how they try to insinuate themselves onto your computer by making it a default install option when you download some legitimate add-on like Flash Player.
But lately, this type of SPAM Search Tools are becoming more and more popular. I was at a laundromat and a lady was trying to get on the Internet. She was puzzled why she could not find her Roadrunner account. In the past, she booted up her computer, using Google as a default page, and then searched for Roadrunner and then found the page, logged in, and accessed her e-mail.
One day, she says, she gets a message "from Mozilla" that she needs to "update Firefox" and so she does. But the message is, of course, false, and the "update" installs a "Search Helper" which claims to be "powered by Google!"
When she searches for Roadrunner, it keeps redirecting her to Comcast, or some competing company. She literally can't find Roadrunner on the Internet.
The search helper is now on a tool bar on her Firefox, installed as the default home page, and installed as a program on her computer. The program even removed the MENU BAR from Firefox, so you can't use the "Tools" link to remove it.
So I show her how to make the menu bar re-appear (right click the top part of the page and click "Menu Bar" to make it visible). When we click on "Tools" and "Add-ons" and then "Extensions" it shows a "Fun Search Assistant!" or some such add-on, which is causing all the trouble. We right click on "DELETE" and it tries to take us to a web page to persuade us not to delete it.
It takes three tries to delete the add-on, but it finally takes. I find roadrunner for her and make that her DEFAULT HOME PAGE. (Clicks "Tools", then "Options" and then "General" and under "home page" click on "use current page" - that is, once you have loaded the current page you want as a default home page).
The fun isn't over, as the program is still resident on her computer. We click on the main menu bar for windows, "Control Panel" and then "Uninstall Programs". The list of installed programs appears, and sure enough, "Fun Search Assistant!" appears on the list as installed. We click "uninstall" and guess what? It tries to load the same page to talk us out of uninstalling this worthless program. We dump that page and hit "uninstall" and check to make sure it is gone for good.
Another friend comes to me with no less than FOUR of these types of "Add-ons" on his computer. It takes some doing, but we get them all off. Now he can search the Internet again in peace.
What is the deal with these types of add-ons and extensions? They are a way of making money - for other people. They want to redirect your searches and generate click revenue for their pages. And what they end up doing is making it harder for you to use your computer.
Are any of them legitimate? Hell, no. No legitimate program installs itself on your computer by using deceptive "negative option" install techniques.
How do you avoid these sort of things? To begin with, when you install a program, be sure to READ all the screens you are clicking on. The typical message you see is, "Most of our customers prefer to have the ASK tool bar installed! Click here to not install it!" And you have to look very carefully and click carefully to opt out. And this applies even when uninstalling - one of these programs asked you to unclick all its components to uninstall it. They rely on you being busy and being used to just clicking "continue" on installation programs (why is it that every program has six screens that require you to click "continue" anyway?).
The other thing is to watch out for pages that claim a new plug-in is required or that your flash player or whatever is out of date. They helpfully offer to have you "click here to update!" If your flash player (or whatever) is out of date, then go to the adobe flash web page and install an update there. Odds are, your plug-in is not out of date, but you have stumbled upon a malware page.
And it goes without saying, that you should run SPYBOT and MALWAREBYTES regularly.
The best approach is to not have ANY extensions on your browser. Plug-ins for Shockwave, flash, acrobat, etc, are OK, but extensions are usually crap, and not surprisingly, Facebook has one they want to install on your browser. Even "legitimate" extensions are little more than marketing tools, designed to sell you to marketers. Just say no to Facebook and all that crap.
And no, this is not a "PC" thing, but a browser thing, largely independent of what platform you are using. So no, spending $5000 on a Macbook won't "protect you" from this sort of nonsense.