Maybe it's a settings issue. I usually rotate my pdfs 90 degrees so I can angle the screen and easily stand and see the slides. I do have the grey bars on the screen but they are not on the projection, or at least they're not obvious. I just swipe my finger across to change slides. I've never had any problem with it zooming by accident. If you have transitions and stuff like that, you need to use an external keyboard and the arrow keys will allow most of those things to work but they don't all work on DocsToGo.

I have to say that most of the time I convert everything to pdf. There are so many conversion issues between mac and pc versions of Office and different versions within each of those and even some problems with OpenOffice on occassion. The pdf is just the safe way to go. If I have something that I think the animation is really important, I'll turn the powerpoint into a movie.