I visit the Microsoft Community very frequently - I have Win10 damage on both my new Win10 and upgraded Win7>Win10 laptops.
Norton continues to be blamed for these problems eg http://answers.microsoft.com/en-us/windows/forum/windows_10-win_cortana/windows-10-critical-error-your-start-menu-isnt/138fade5-5f05-48c5-abe9-0260afd2491a?page=2
I know I've mentioned this problem (Norton being blamed) several times before but I can't find them so may I suggest that a Moderator creates a Sticky where we can record all these claims?
If End Users keep blaming Norton, it's bound to have an effect over time.