Check out the following article; it may help:-

http://support.microsoft.com/kb/919196

If my comments have helped please hit Yes.

Thanks.

"wtaipan" wrote:

My excel program will not open files when I try to access them from anywhere
other than Excel directly. Eg. Outlook attachments, My Documents, Desktop.
If I find an excel file in My documents or as an attachment in Outlook, and I
double click it (or right click and open) my Excel program will open but the
file will not. I have to save any attachment to my computer and access it
through Excel.
Any ideas?