Excel 2003 to Excel 2007 graphs
 

I have a bunch of Excel 2003 graphs that are now being updated with
new data. In the course of this, we are also saving as Excel 2007
macro-enabled files (.xlsm). Any time the file is saved it has a
message invalid name or range and says it will change the name to
"_CHARTA_xxyy" for example. You are prompted to say "okay" or "okay
to all". If I follow it through, there are about 82 instances of
this, so I figure it has to do with components of the graphs on the 2
worksheets. There are a total of 4 graphs. Any quick solutions to
this compatibility issue? BTW, the macros in the file work fine and
the graphs come out just fine, just the "okay" question comes every
time a save is done.