Crash by removing instruments with parts in a certain configuration
Steps from scratch:
1) Create new score, 4 measures, for: 4 flutes, 1 piano, 1 flute - in this order.
You get this test file: test parts.mscz
2) Create parts (New all/OK)
3) Press "I"
4) Remove the three last instruments (ie flute, piano, flute)