Togo's advice is sound but there might also be something on your laptop which is either directly generating those pop-ups or making a call on a remote website to do so.
So CAC's advice to go into you list of installed apps and uninstall anything that mention Norton also hold true.
Further, a malware scan wouldn't go amiss here. If you've already installed the free version Malwarebytes Anti-Malware onto your laptop, then run that. (However I no longer recommend a fresh installation of that program, as it comes with a free trial of the full software, that seems to slow some computers down quite a bit). Otherwise download and run AdwCleaner (it's 'out of the same stable' anyway). There's no installation process; you just run the downloaded file directly:
https://www.malwarebytes.com/adwcleaner/