Same issue, but some more detail on my side.
The document that is being converted from 2007 to 2003 format was originally a 2003 document. It has numerous calculations, controls, and VB scripted macros. Opening it in Excel 2007 works fine, everything works.
However, if that file is saved in 2007 as an XLSX or XLSM spreadsheet, and sent back to us to open in Excel 2003, the file conversion fails.
That file can STILL be opened in 2007 with no errors, however, and does not require repair.
Seems like the Office 2007 Compatibility Pack requires some tweaking. Please advise if there is a workaround (other than asking our clients to ensure they save the file in 97-2003 format...which we have).
Thank you!