Peter,
I am pretty sure that the problem is in your parameter script, especially when you're using CUTPOLYA with calculated parametres or moveable hotspots etc. where incorrectly calculated values distort the cut plane. similar problem gave me a real grief lately.
the parameter script is a bit tricky (it seems to be run twice along with the master script) so be careful and test it properly.
Actually my wish would be (and I am going to put in GDL wishlist) if we could get reasonable explanation/description how's that bl**dy thingy (meaning the parameter script) actually work from GS.
::rk