I installed Windows 8 on Christmas Day and I skipped the email account setup parts. I never used any APPS yet, in fact I removed everything app-related from my start screen including notifications, etc.
I have used the Classic Shell so far, but today I thought I'd set up the Live email account login.
While I was setting up the app account I kept getting emails from the live account manager to confirm what I was doing and I confirmed each one.
The last thing it asked to 'Trust this PC'. I did so and my machine name appeared on my Microsoft account profile page under "Trusted PC".
But when I restarted I could no longer log in with my local account or the new Live email account.
I logged in as Administrator and saw that my local account name was changed from my username to <firstname.lastname@example.org>, my live account ID. It would not allow Administrator to change the account name or my password.
I tried to log in with the email and Live password, but it said I could not log in with his PC and that I need to resolve the issue with the live account on-line.
I had a password reset disk (USB drive) and I used it. It started up the reset wizard and I put back my old password. It finished with no error but I still could not log in.
Finally, I logged in as Administrator and restored my Acronis system image from yesterday. Then everything was back to normal.
I have no idea what happened, I was very careful doing each of these steps.
I see a clue, though, on the Microsoft account page in the Trusted PC area is says:
"To add a trusted PC to your account, you need to access your account using Internet Explorer and have Windows Live Essentials installed."
I was using Chrome to set this up and I don't have Live Essentials installed. There was no indication in the set up that this was required. But, at any rate, it still listed my machine name as trusted, so what does that tell you?