Whenever I try playing on a multiplayer game, such as my SMP, I get a response saying "Failed to login: null." I first noticed it yesterday, and the message has still popped up whenever I try opening any multiplayer server. Single player works fine though, but I'm mainly concerned about the multiplayer malfunction. I tried googling resolutions, like reopening mc and logging out and logging back in, but none of those worked. Even to this day I still get the null message.