I haven't had time to look into it more, but Norton is certainly not part of the issue for me. Like Al, I remove any Norton product, as well as any other bloatware that comes on my computers.
As a side note, I've been running the standard Windows Defender for years with no issues. I don't visit questionable websites, don't download anything or open anything unless I explicitly trust the source, and my browser/virus and spyware definitions/operating system are always kept fully up to date.
-Kevin