This is a problem haunted me for so long, it occurs when I use "Kontakt Factory Library" strings Kontakt is plugged into a stereo instrument track in my Pro Tools LE 8.0.4 Assume that the string session start in the middle, I will have no problem playing back or recording the part before that. And when the session starts, I stand about 85% of chance to have the following 2 outcomes. First, it halts, and show me a message box, "The audio device underflowed. If it occurs frequently, try decreasing the "H/W buffer size" of the playback engine panel or remove other devices from the audio fireware bus. (-6085)" Or worse, the whole machine freezes and response to nothing except the reset button. What can I do for this, please?