Cannot advance or go backwards in slide show w/mouse

[Tara]

This is one of the strangest things that has happened on
my computer, at least lately. I have a presentation that,
no matter what I do, will not allow me to use the mouse to
advance or go backwards while viewing the slide show. (I
have to use the keyboard).

Anyone ever had this problem? Any solutions? I have
looked at ever setting I can think of and can't seem to
track down the problem. It's the only one of many, many,
MANY presentations I am working on that is doing this.

Thanks!!!