My computer is a 2011 I-Mac 27 that runs version 10.12.5 mac0S SIERRA.

I normally have about 10 Tabs open all the time. I get most of my NEWS from the YAHOO site. For several months, I have had a problem with the Yahoo tab. I am cruising along, minding my own business when suddenly the screen goes blank and then up comes a request for me to participate in a survey for Bell Canada.

It does not matter whether I use Safari, Chrome or Firefox. I am not all that experienced with computers so I have no idea how to get rid of this virus. Is there a program out there that will DEFINITELY kill this annoying bug?

Any help will be very much appreciated. If you need more information, kindly ask and I will do my best to provide it quickly.

Thank you in advance,

Tom