World Of Warcraft keeps Crashing. Please help!?

So i downloaded World Of Warcraft, and it was fine for the first day. But ive been playing as its been downloading. And all the sudden it would freeze. And then it turn to a blue error screen. It would have a long error with 0s and xs and stuff like that. It said it be a good idea to error check, and Defrag my disk. So i did. And it still is doing it! I'ev done the first 4 steps on technical support about crashes. And i really still cant figure it out. It tens to crash sooner once i go into a Instance/dungeon. Please help me! I really want to just enjoy my game. Thanks you very much.