Error "excel found unreadable content in filename.xls. Do you want to recover the contents of this workbook?..." appears after saving an excel file to an network location from outlook email.

Hi Excel experts,

sorry for my poor English.

my situation is: I open an read-only excel file (.xls) from an outlook email directly and then click Save button in the file to save the file to a network location. The file is successfully saved. But when I open the file in the network location by using excel 2010, the following error appear:

"Excel found unreadable contect in 'filename.xls'. Do you want to recover the contents of this workbook? If you trust the source of this workbook, click Yes."

then I click yes, all formatting stuffs in the excel file is removed.　Could any expert help?

Thank you so much!!

Jason