It's either your computer or the rendering system I believe.
If your Rendering system is OpenGL, change it to DirectGL and vice-versa.
To change it:
If a white square comes up before your game starts, at the top will be your Rendering system. You can change it to another by clicking the arrow on the right. If this doesn't happen, open your full game and on the Login Screen go into Options.
Go into 'Video' and it will say 'Rendering Subsystem' your present one is highlighted. Click the one that's not highlighted// the opposite one to what you have and restart your game.
Hope this helps! :oo