CRJ RNP Approach Freeze

I seem to be having an issue where as soon as I attempt to load up a complex RNP approach such as RNP Z 15 for Paro or RNP Z 23 for Queenstown my sim completely freezes and I have to end the task using task manager. I believe this has only happened to me on the Aerosoft CRJ with RNP approaches. It should be noted that making extensive modifications to the flightplan or FMS cause lower frames (a decrease from 30 to about 8-10) possibly indicating that these occurrences are related. It may be that these RNP approaches are too complex and cause the sim to freeze. I do not know.

Many thanks,