I have done some further research on the multi-port USB MIDI problem that I have been encountering with the default USBAudio.sys driver. The driver will accept the first few MIDI events (SYSEX Messages, notes, etc…) then will stop working for a few more messages, then will start working again for all messages after that. I was able to reproduce the issue using a third party MIDI device that has multiple MIDI ports for a single USB device. The third party MIDI controller created their own USBAudio.sys driver to compensate for this short coming in the default driver. My question is what steps should I take to create my own USBAudio.sys driver? Is there a sample driver that is recommend I start with? Timothy Knudtson iConnectivity