Issues with Vegas Studio

So I've kind of been working with Vegas Studio, and I've run into a black screen problem.  The project version plays of my video plays, but the rendered version does not. (.mov, .wmv, .avi formats)  The rendered video shows up black, but the still screens remain (pictures, text, etc.)  Also, the sound is in tact.  I don't think it is a codec problem because when I replay the rendered video in Vegas Studio, it doesn't work, either.  Any thoughts?