Few quick questions--does it reliably do this, i.e., every time, same place? Does it replicate across machines? If you switch the order of the three input files that you are executing through MediaLab, does it still wait for the third to freeze? And finally, if you are able to pin it down to one input file or another--does it freeze when running on its own with DirectRT--i.e., out of the context of MediaLab?