Anybody use windows movie maker?

I have a problem with it.

When i go to add a video little clip (its only 20 seconds long) and add a tack with it, the track sounds really bad. Its like slow, bad quality just not nice to hear. But when the video clip ends the track is fine again. So obviously its something to do with the clip running with the track at the same time. Does anyone know why it does this and how to make the track sound normal?

As you can probably tell, im rubbish with stuff like this so help would be much appreciated.

No no. The clip that ive added doesnt give out the sound. Im ADDING a track to it. To make it have some sound, but when i do it goes all weird.