How to remove blank space at end of movie project

I've created a project in Vista Movie Maker which was 15 minutes long at one
point. Later, I shortened the final audio and video clips to make the project
11 minutes long. There is nothing on the Timeline after the finals clips, but
the project insists on playing through the blank space after the clips to the
15 minute point anyway. How do I get the project to cut off after the final
clips are done?