Disable Next button until all lightboxes are viewed?

Hi all,

I have a slide with 5 lightboxes. The lightboxes are actually other slides within the same scene.

On the base slide, I would like to disable the Next button until after all 5 lightboxes have been viewed. Is there a simple way to do this? (And, would it make any difference if I put the 5 lightbox slides in their own scene?)

Thanks,

Mary Ann