If your getting this view in your playback when right before it was shadded and looked fine then it usually means your computer can't keep up with the playback do to your lack of resources from your graphics card, ram, CPU Hard Drive or other computer process.
You could try lowering the shading type to constant shading and see if that helps. It looks like your trying to render a bunch of particles so it just might be too memory intensive for the playback to handle. You may want to lower the amount for playback purposes then ramp it up when rendering.
Also, if you like the animation of your particle system and aren't planning on changing it, you could "Bake" your particles so that the computer doesn't have figure out the math every time it is playing back, thus giving it more resources to play the other stuff in real time.