It's happened a few times and it is rather annoying. While editing a project all of a sudden there will be no video showing in my monitor. The background music is playing but no video.. I think it has something to do with moving the bar at the bottom to move along my project ? Not sure. In order to fix it I've had to save the project and then re-load my project and voila.. my video is back. Any thoughts on this as to what my problem is?