Tech scams are rampant everywhere, KB ~ first, in explanation, I got rid of Norton years ago after a similar episode to what you describe ~ BTW, Norton is VERY difficult to get rid of ~ it has bits and pieces everywhere ~ Jab linked up with me on TeamViewer and he taught me some very "colorful" language while searching out Norton's bits/pieces on my computer ~
I've never used 8.1 ~ I went from XP [still my fave] to Win7 [which I learned to like] to Win10, which I like a lot NOW ~ I'm using Windows Defender [free], which is working well ~ I update it regularly ~
Along the way I found
Iobit's AdvancedSystemCare ~ there's a free version ~ it's a scan that covers virtually everything ~ after using the free version for a while, I upgraded to the Pro version [it's cheap, something like $10/year] ~ it even scans/updates drivers ~ I rely on it daily ~ the full scan only takes a few minutes ~
My advice [FWIW]: download ASC [from the link above] and run a scan ~ warning: the first couple of times you run it, it will find a LOT, especially if you've been having problems ~ when the scan completes, click on "fix" and let it do its thing ~
Happy to answer any questions you may have about ASC ~
Sooz