ok i just started minecraft on a very nice computer and whenever i play the game it runs so slow like i take a few steps and then it freezes for 30 seconds, and thats just singleplayer multiplayer just loads the application turns black then crashes. am i missing something here? all i do to get to the game is go here (http://minecraft.net) and press on one of the two minecraft classic buttons, do i have to download something extra so i can play this or what?