It has to be something with your setup. I built a quick cd this morning and rendered out an animation fine using batch render. Didn't do anything special. I lofted 4 circles for the cd, applied the diffraction shader to the main body of the cd, set a few keys and rendered out a 75 frame animation (tif sequence) at 30fps. Imported the files into Premiere and exported as avi using divx 5.0.5. The result is the attached movie.