I have been editing with Vegas Movie Studio (Platinum 11.0) for several years with no problems. Resently while editing a short video I started to get a red flash that covered the preview window on a few places on the timeline. Occasionally the screen will go red and stay that way until I stop the video. Although the points where the red flash occurs are similar each time, they are not always exactly the same. I've examined my edit points and nothing appears to be different from other points that are not having the problem. What could be causing this?