Create a new local user and make it an admin account. I'm running into a lot of new users that don't know about this and run a PC as if nothing will go wrong.
If you are using Microsoft's Email login, back to Microsoft for support. I don't use the email login system and don't have the issue you wrote about.
I do have some ideas that may be playing into your issue. If the machine has internet connection issues on resume from sleep or such, login can fail if it's that email login. You have to fix the internet connection issue to cure that. Microsoft does not make your PC so you're sort of on your own for that issue.
I just installed Windows 10 Anniversary Edition on my private PC, and it refuses to accept my password when I try to log on at startup. The only way I can get the operating system to accept my password is to do a restart and submit the password again. I never had this problem with earlier editions of Windows. Does anyone have an explanation and a solution for this?