Excel Spreadsheet opens in Outlook email
 

Hello,
I have a spreadsheet that has worked well for months, but all of a sudden,
when I double click it to open (from explorer) or even Rightclick, open
withExcel, it opens in a new Outlook email message, not as an attachment but
the spreadsheet seems to lose it's formatting and is in the body of the
email.
Also, if I close the email, the spreadsheet closes, BUT , If I send the
email, THEN the spreadsheet is then opened as it normally would...
There are NO macros in this sheet...
Help?