David:
Thank you for your help!
I did as you suggested, changed the option to show in a window, and
saved the .pps file.
However, when I then launch it again, it still takes over the screen.
Given that it opened in a window when I used File>Open and that it
behaved differently (took over the screen) when I just opened the file
by double-clicking on it, there is a very serious fatal bug in
PowerPoint. One of the very basic assumptions that has always been
true on the Mac is that file>open, double-click and other methods of
opening files are exactly the same. Microsoft seems to violate this
rule.
If you (or anyone else here...) know a workaround so I can open
the .pps file directly (double-click on the file) and have it open in
a window, I would very much appreciate it.
Also, does anyone know how to tell MS they have a bug?
Thanks!!