My guess would be protools has midi thru turned on, and so has the midi keyboard, so your note off messages are going around in a circle. Check the data in protools. Can you see the notes are the correct length on the screen? I assume the keyboard is a synth and protools is connected back to it to use its internal sounds? If so the keyboard sent an on and off message for each key press, protools records it but sends it back a fraction of a second later, but the keyboard plays it again, and send that back to protools. I suspect for every note you played you will find many duplicates, and the keyboard is running out of polyphony which cuts notes dead when the next one comes in.
Hi Rob thanks for your help (sorry its taken so long for me to reply).
I've tried zooming in but I cant see any duplicates.
Is there anything else you might suggest?
I have a video of how it looks/sounds, is there a way of uploading it to this forum?
You can rarely see them because they are in exactly the same place. However, if you want to send me a MIDi file - not the protools file, I'll have a look and see if I can see something. firstname.lastname@example.org will find me.