2003 to 2007 graph editing

hello all: I am attempting migrate files from custom template in 2003 to
similar template in 2007. I am running pp2007 with sp2. I have created
a new potx and thmx file as well as several chart crtx files. When I
open a ppt file and attempt to convert the graph files, I get hung up.
If I use "edit existing" then of course ms graph pops up. If I choose
"convert" then a new popup says "one or more charts in this document
cannot be converted to the current Microsoft Office chart format". the
process does not allow me to convert to excel based data sheets.

Sometimes I get a popup which says "to insert a chart, you must first
close any open dialog boxes or cancel editing mode in Microsoft Office
Excel"

Randy