Have you ever gotten those scary popups that tell you to call Microsoft because you have a horrible virus swimming around in your computer? A lot of people have. It's not an uncommon experience to have online.
The best way to handle them is to shut down your browser and open it back up on a different page. Never allow anyone to take control of your computer unless you are positive that they are legit. If you get these popups while surfing the web, your computer doesn't have a virus and Microsoft will never ask you to call them. Ever.
Want to know where some of those popups come from? Watch this excellent video from Jim Browning and find out who runs the scams and how they operate.