If the workbook you opened was created in an earlier version of Excel you will
get the "save changes" message.

Save as 2003 version.

You will also get the message if you have used any volatile function(s) in your
workbook.

Could be a  NOW()  or TODAY()

List of volatile functions........

AREAS()
OFFSET()
CELL()
INDIRECT()
NOW()
TODAY()
RAND()

Any one or more of these would cause the workbook changes.

Gord Dibben  MS Excel MVP