Keynote won't play video after saving

I am using iWork's 09 Keynote to build a presentation for my Leadership class. For one of the slides, I have a video (first tried mp4, then tried .mov). When I initially load the video into the KeyNote Presentation, it plays fine. But when I save the presentation, click on another slide, and click back to the slide with the movie on it, the video will not play! (Green screen w/no audio when it's an mp4, scrambled colors w/no audio when it is a .mov) I have never had this issue before with loading videos, has anyone else experienced this, and if so, how did you fix it?