Cannot copy a worksheet to another workbook...

I have a basic question that I cannot figure out. I am using Excel 2007 and want to copy a worksheet (saved as an Excel 97-2003 file) to another workbook (also saved as an Excel 97-2003 file). When I go through the steps to copy it, I get an error message that says,

"Excel cannot insert the sheets into the destination workbook, because it contains fewer rows and columns than the source workbook. To move or copy the data to the destination work book, you can select the data, and then use the Copy and Paste commands to insert it into the sheets of another workbook.

I need to keep this as an Excel 97-2003 file because files are shared across our company and about 1/2 of the people are still using Excel 2000. I can copy and paste the data manually, but I lose my formatting (even with the "Paste Special" option). It's a pain to have to do this every week when this report is due. I was wondering if someone had any ideas. I didn't have this problem when I was running Excel 2000.

One last piece of information. I run a Excel 2007 macro to manipulate the data on the worksheet before it is saved in a 97-2003 format. Could that have anything to do with it?

Thanks in advance for any help,

Chuck Norman