I need to edit a slide show dvd?

I made a dvd slideshow for my daughter's sweet 16 birthday party a few years ago. I want to add more photos to it now to show at her graduation party. The files on the dvd are .VOB, I think I made it in windows dvd maker or movie maker. I can watch the slideshow fine, but if I open it in windows live movie maker to edit it, all of the thumbnails are squished vertically so I can't tell which ones to edit out. Can anyone help me with this?