I finally found the problem. I remember that it never occurred back when I ran MC15, but running it again I found it still crashes. When testing other programs that I am running now, I found that it was conflicting with Actual Multiple Monitors. Another problem to go under Weird and Wonderful, I guess.
Thanks for your help!
Edit: I added the Display window as an exception in the Actual Multiple Monitors window placement and now they both play nicely together. Yay!!!
Edit 2: FYI, the latest version of Actual Multiple Monitors fixed the bug.