Sorry for the delay, I saw it then promptly forgot about your post ~ playing the age card here
I just tried it in FastFlick as well as VideoWave and do not get any distortion either in playback while in the editors or playing the file I created with the editors.
That is of no use to you in resolving your issues... I will ask some of the other gurus to take a look and see if they can help resolve this with you.