File format is not valid

[TJS]

I created a spreadsheet at home on my computer using Excel 2007 and e-mailed
it to my husband at work. He also uses Excel 2007. He has been using it
there with no issues until today when a user attempted to open it and got an
error message saying that the file extension was not valid. I had him e-mail
the file to me to see if I could open it and I am also having no luck. The
file extension is correct -- .xlsx -- and I get a different error message at
home. I am being told that the file format is not correct. I am not sure
what could have happened to the file, but I need to find a way to open it and
fix it for him.

I have read some postings and tried using OpenOffice without any luck. Any
help will be greatly appreciated.

Thank you.

[bobby02169]

Hi TJS,
I am having the same problem and get the following message when I try to
open the spreadsheet. "The file you are trying to open, 'Blank INVOICE.xls',
is in a different format than specified by the file extension. Verify that
the file is not
corrupted and is from a trusted source before opening the file. Do you want
to open the file now?"

Have you found a solution to this problem?
Thanks
Bobby