Damaged Excel File

I have an extensive excel workbook done in Office 2002. Many worksheet are liked with formulas and formatting. My standard use of this workbook is like this: I open the "blank" version of my workbook, input varialbe information, and "Save As". When I try to access the saved document I get a message that says "Errors were detected" and "damage was so extensive that repairs were not possible...excel tried to recover....some data may be corrupted".

My workbook contains most of the information I input but the formatting is messed up.

Any ideas on how I can save this without corrupting.

One note- I have been using a previous version of this workbook with no problem. I have recently updated the workbook to combine some worksheets with formulas. I was not having problems with this "save as" function before I combined some of these worksheets together using formulas....is there any way to know what caused this damage so when I redo the combined worksheets I can do it correctly!

Thanks

Jim