What happened? Please provide more details. Such as where it happened, how do you recreate it, and how what it does.
http://www.pcworld.com/article/3164453/hardware/nvidia-releases-hot-fix-after-game-ready-driver-breaks-minecraft.html thanks that helped me find this link PCWorld has a better fiX then to downgrade I recommend you spread word around
I think this might be a website problem not a problem with the game. The name might be blocked by Mojang.