OE won't open Power Point slide shows

Whenever I try to open a Power Point slide show attachment in Outlook Express,a message appears saying: "This file does not have a program associated with it for performing this action. Create an association in the Folder Options control panel."

I have been to the Folder Options in the control panel and found the Power Point slide show icon and associated file PPS are listed there. When I save the attachment from Outlook Express to My Documents it opens without a problem.Can someone please put me on the right track.

Thanks!