Excel Web Access - Unable to Load Workbook

The Excel web access will throw the following error when the associated workbook is created using Office Excel 2003 / lower.


Error:
The workbook that you selected cannot be opened.
The workbook may be in an unsupported file format, or it may be corrupt.








Use Office Excel 2007 to create the workbook and save it to your library (trusted location) and now the Excel Web Access web part will display the workbook.