Sonar's matrix view - How to get audio clips to trigger from the start of the clip?

I'm using 8.5 Producer, and decided to experiment with the Matrix View since Beatscape and Cyclone are driving me to pull out my hair. Well, so far so good, except for this total dealbreaker: If I trigger a 2nd clip from my keyboard before the 1st one finishes, the 2nd one will start, not at the end of the clip, but in the middle somewhere, and will cycle back to that point(instead of stopping at the clip's end). I'm ready to break the laptop. Anyone know how to fix this? Isn't there a "MIDI choke" or something, that will cut off the 1st clip when I trigger the 2nd, and start that clip FROM THE TOP?