Quote - PoserPython is 2.1?!?  I thought it was 2.23.  

No wonder I'm confused....

I was referring to the version of the Numeric module not Python.
The reason I mentioned it, is because this is a very old version (4+ years, source code only available from the numpy CVS at sourceforge).

Thank you.  I'll look into numeric.  And gc.  And None assignments. 
Upon reading a bit more about garbage collection, I think the gc module may have failed for me because I have circular references in place.Python should cope with reference cycles, but extension modules have to correctly use the relevant API calls, so possibly Numeric and the poser module may not be doing things that they should be to avoid trouble.