Looks like it is specific to dosbox somehow. With the earlier versions of the index program, even fullscreening an independent dosbox launch while the program is running causes the crash. That is true even if I launch notepad first. But if the program launches notepad from inside then there is no issue (except that notepad is open). With the latest program, I'm launching another mmf program and killing it before dosbox launches, and that works. But I think it was working in one of my versions so long as I do it before dosbox fullscreens. A little more elegant to do it before I launch a dos game at all though.