A family of Microsoft presentation graphics products that offer tools for creating presentations and adding graphic effects like multimedia objects and special effects with text.
I've run into this fairly often, mostly when an object on the slide has a reflection. PPT considers the reflection part of the size of the object, so it makes me have to scroll my mouse's scroll button more than once to advance to the next slide. Even if you can't see the whole reflection, it basically doubles the size of the object....
It also happens sometimes if you have an object that's hanging off the edge of the slide layout in slide master view. It doesn't have to be off by much,, either -- just a hair seems to trigger it.