The crackling should be gone from the begining, if you installed everything clean. (could just be that your computer is a bit slow) There is some crackling in certain levels due to a bug in the sound stuff. Basically, we discovered that every ambeint sound (insects, fire, wind, etc sounds) in the sector was always playing, if just muted from being out of range. I added a new emitter generator to put lots of these in (ex: attach fire sound to all torches; attach insect sounds to 30% of a kind of tree) so we have signifigantly more 3d sounds than before. This made the sound bug really noticable. I've already fixed it in CVS, and we'll post an update with this and a few other things when we setup the update servers,