I'll answer my own question! Somehow, several items in my to-do list ended up with a Priority of 0 (it's zero in the ical file, shows up as a blank in KOrganzer To-Do view). I really have no idea how that came to be, BUT when I set all those zeros to 3's, it fixed the printing problem.
So this is probably a bug: either the problem of some To-Do's getting a zero or blank priority somehow, and how having a zero or blank priority makes the printing freak out. --isaac
