Pinnacle Studio 18 Plus, problems previewing in movie window.

I have tried several projects using still photos, video clip ( both commercial & homemade), and a combination of the two. Everything works fine until I try to preview the projects in the movie window. The images continually flash off & on during playback. The music track plays just the way it's supposed to. Any help would be appreciated. I can't get anywhere with the Pinnacle or Corel people.