NEIKEv2 Provider Keychain
In past few days Norton locked me out on my Macbook Pro by using something that asked me for NEIKEv2 Provider Keychain password. I tried searching Google and ending up in Apple and Norton support forums to find answers. However, they did not help solve the problem. The solution was that the login/sign-in screen password is the same NEIKEv2 Provider Keychain password. If you enter log-in/sign-in into NEIKEv2 Provider Keychain password box and click allow it and proceed from there the problem will disappear.