Facebook infected advert

When I am into Facebook, on the right hand side of facebook, I get a few adverts or news items.

When I access them, not every one, I get locked out of my computer and informed be a message on the screen to call a special number, which as we know is a scam.

 

So, how do I know which advert is a "lock out"?  and why does not Norton detect and destroy this please?