Further information based on our efforts to figure out what is going on:
a) The program locks up after a certain number of responses have been made, regardless of how many experiments are run. I.e., somethings (Vista?) is tracking the total number of responses. We can run through a whole experiment that is lengthy but not long enough to reach the lock up point, then start another experiment and the second experiment will lock up quickly as it reaches the lock up point (based on the total responses across both experiments).
b) If we run an experiment, close MediaLab, and then run a second experiment, the total number of responses factor resets to zero.