I've experienced crashes, random closing, and also a corrupted tax return.  For the corrupted tax return I went through having to re-install ProSeries and losing all of my original settings without being able to save the tax return.  The first tech support person I spent a half-hour with finally admitted that it was his first day before passing me on to someone new.  I don't appreciate ProSeries's disregard for my time this way.  A good part of a day was spent just dealing with all the fall-out of the corrupted tax return, which they never could explain - "just happens, sometimes".