Why do I need the midi cc reset ?

I have my TB-03 Bass Line slaved to the MPC1k. When I unmute the tb-03 tracks (sequences) on my mpc it sounds great and everything is normal. But when I unmute something else and then come back to the original Bass Line sequence it sounds aweful, like the notes aren't being played fully. Like they are a bit detuned, but not like a 'proper' effect...it just sounds really wrong.

However, when I press the "cc reset" in slider mode of the mpc, my tb-03 sounds good again. Unfortunately I cannot keep doing this while also trying to perform the song.

Does anyone know why the cc reset works to clean up the midi signal from the mpc to the tb-03? I think if I understood what was going on with the midi communication between these two instruments I could solve the problem. I should mention, my other synths including the boutique Juno 6A, are working fine in this set up.

I did upgrade the OS at some point from OS3 to the newest version....would this cause any problems with my midi?

Any insight would help greatly!!!!! I have read manuals, forums and contacted Roland....so far no dice.

THANK YOU

Find a way to hook up the devices to a computer so you can read the midi traffic.