Attempt to sign in offline or without any access to online services.
If you are able to sign in offline go to File, Password manager and remove
your email address.
Then close and reopen your money file and go once more to File, Password
manager and add your live id, this normally happens when you change your
windows live id password, if you did try all the passwords you have used
since then.
Otherwise if that does not work try restoring a backup file (*.mbf) and
attempt to sign in.
Hope this helps.