[digidesigner]

I do not mix on my m-powered laptop, I just record mixdowns with it from my PT mix system if it has all tracks in use. But I always run my MIX system thru my m-powered and output all sounds to speakers thru my M-audio Lightbridge. So I sometimes have stereo tracks at my m-powered pro tools (different versions of a mixdown) and I have noticed, that when playing back the tracks my system makes weird noises time-to time. It makes some "ZAP" and "ZIP" kind of sounds in random places that are errors not in the waveform. I tried to locate the problem and changed the buffer size for that (I use 1024 usually) and after just changing the value to something different and then changing it back will make the error sound go away for a while. Maybe thats the same you are getting.