Going to Properties, reveals that they are .xls files.
Opens with: line says "Unknown application."
Clicked on the Change...button
and clicked both the 2003 and 2007 Excel icons to Open With - but nothing changes.
have you tried to verify/set those icons for 2003?
Since the install of 2007, the icons look similar to a MS window with 6 little "squares" in the middle of this window. Typically what you would get if Windows can not identify the program to use to open it.
Second question, will 2007 still run .xlm macros?