[Avid Product Design]

Thanks for the additional details. Please try each of the following in turn and let me know the results:

1. Set Pro Tools SE > Preferences > Audio to "Mixing or Producing".

2. Unplug the firewire hard drive and try saving the session on the internal drive.

3. Unplug everything except the Micro USB. Make sure that the Micro USB is in the USB port nearest to the front of the computer.