I have a .XLSM file created in Excel 2007 that contains a function to copy several worksheets into a new Excel file. When my user runs it in Excel 2010, she gets the error message:
Run-time error '1004':
Excel cannot insert the sheets into the destination workbook, because it contains fewer rows and columns than the source workbook. To move or copy thedata ... "
This is what I don't understand:

1. Normally you get that message when trying to copy a 2007 worksheet into a 2003 file, but how can you get it too when it's opening in 2010? The 2007 file is a .XLSM. The 2010 should be a .XLSX default.

2. My user is the only one in her organization using 2010. The rest of the organization are still on Excel 2003. Could it be possible that she set her 2010 default file type to .XLS so that the rest of the people can read her file? In that sense I can understand that the file her Excel 2010 creates is a .XLS file. Is it possible to pre-set Excel 2010 to start new document as .XLS? I only see it in the Excel Options that you can set the default Save format but not new document format. Are they equivalent?

Thanks in advance for your help!