From: V-2stumc on
when using Excel 2007 to open a 2003 workbook, It opens fine, but because of
the number of formulas, and the fact that it is linked to two other Excel
workbooks, it takes more than 25 minutes to save, excel goes unresponsive,
and the CPU usage of the computer goes to 100% (50% on dual core systems).
if we open the same workbook in Excel 2003 everything works fine. It will
save the workbook in about 10 - 15 seconds.

We have already tried loading the workbook on another machine with office
2007, and using the file on a machine that has Office 2003 (which works), and
looking for KB pages or other forums about this issue. It appears that I'm
not the only one who has had this issue, but I cannot find a solution to this
issue with the resources that I have used yet