It appears that I am one of many sharing this problem.
I am the sole account holder and my BT ID is my xxx@btinternet.com email address; alas the problem still persists.
Assistance to fix would be much appreciated.
Solved! Go to Solution.
Issue resolved; BT links to Norton must be solar powered!
Access through MyBT>Your Products>Broadband>BT Virus Protect(scroll down to display),
This redirects your browser to https://my.norton.com/extspa/dashboard/Home.