A similar post had a solution (reinstall), but I did not need that. This is what worked for me.
I did a Live Update that installed something that took a long time. Not fixed. Then I downloaded and ran the Norton Power Eraser, which does a deep scan. This tool required a reboot. The result was that it said something like no problem found. The Quick Scan error message still was there afterwards when opening the Norton Internet Security app. However, this time when I clicked to run the Quick Scan it actually ran. After that all was ok.
Part of me thinks stronly that the fix was actually by the required reboot of the laptop. In all my days of being an IT consultant, whenever there was a computer problem, reboot was the first thing done usually. That sure fixed a lot!
Your other post that is the same as this one was posted before this post - thus that is the original and this is the duplicate and why I asked for it to be removed.
In order to be able to add the "Email me when someone replies" to posts, all you have to do is select the Reply Button and it will display that option. You can then type your reply and check mark that email option.
Also be advised that the Edit Button disappears after the post has been on the board for one hour. To delete a post within that hour, select Edit and then erase (delete) the text and state - post deleted.
Hope this helps - I will also post this on the thread that I already responded to.