Erratic embedded spreadsheet behavior

[Gentex]

I have an embedded Excel 2002 spreadsheet in a Visio 2002
file. I created the spreadsheet from within Visio, so it
shouldn't have any pre-existing problems. When return to
Visio after editing the spreadsheet, I get what appears
to be an almost random variation of object placement on
the page, visible cells, and object size. Neither the
spreadsheet nor drawing are particularly complicated.
I'm open for any ideas.

Thanks,
John M.
Genetx