Does this happen with every model?  There is a long running problem with some versions of DAZ V4 where buggy morph data in the eyes causes Poser to crash when touching the morph brush.

Poser shouldn't close when you hit ctrl-z, it should undo (which I'm sure you know), does it always exit when you hit ctrl-z, e.g. when just looking at a blank document or in other circumstances besides using the morph brush?

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