Anne, you  wrote on Sat, 30 Jun 2007 07:38:00 -0700:

You need to have installed Microsoft's Powerpoint or its costfree
Powerpointviewer [1]. If you have installed one of this programs: What
happens when you attempt to open a pps-file?

[1] http://tinyurl.com/yyzosw

For future reference, add the following to your browser's bookmarks to
determine what program you need to handle a particular filetype:

http://filext.com/