Sign in bug

There seems to be a bug that doesn't allow some people to log in to their minecraft accounts. This could be do to the recent update Mojang did, however it is a major inconvenience when you know your username and password but both Minecraft and Mojang locks you out. Even when you request a password change it still doesn't let you log in claiming it doesn't know you. Yet if you try to re-register it tells you you are in the system. It would be nice if when Mojang claims to have fixed all their issues, it's because they actually fixed everything.