Windows 7: Powerpoint 2007 randomize macro, trouble with hidden slides

I have added a randomize macro to a presentation and it works fine, except when it comes to some hidden files I had in the presentation. I only want them shown when linked images from a previous slide are clicked, but I don't want them shown randomly. Is there a way that I can specify in the macro that I only want to randomize to another unhidden slide and not the hidden ones? Here's my macro:



ActivePresentation.SlideShowWindow.View.GotoSlide Int(Rnd * ActivePresentation.Slides.Count) + 1

Thanks!