Im sequencing my rytm on seperate instrument tracks in PT11. But after a couple minutes I get dubble notes from some drum tracks. like 1 extra note when realesing the key(only in keyboard, not rytms pads) and some other problems like notes are flanging/rolling, etc, messes everything up, need to restart the rytm to get it normal, but it always comes back to that error mode… 
anyone know anything? cheers
Midi feedback loop possibly?
I have only 1 cable connected, no usb or usb out :-/
Use a midi monitor to see what being sent out of pt11. Make sure there is no unwanted info being sent.
0002EA24 7 10 90 1F 7F 1 G 1 Note On
0002EB6A 7 10 90 1F 00 1 G 1 Note Off
is being sent. Used my midi keyboard, eps16 keyboard and mpc ren, all the same thing. In Pro Tools and in Cubase. All the same thing.