Just ran into this today: if you have IV and an Excel spreadsheet open and
are editing a field, inserting an iPart will not work (the iPart dialog will
not display). If you commit the edit in Excel (hit Enter or just save and
close) then you can insert the iPart normally. I don't see how this would
happen very often, but I hope this saves someone the aggravation it caused
me.
Cheers!
Alan Rennick