Windows Movie Maker changes the pitch of the music

Hi Everyone:

For some reason, Windows Movie Maker 2012 version changes the pitch of the music of a karaoke project. I imported the music, laid down the lyrics where they should be, and when I was done, the music had a higher pitch than what I started with. Consequently, I can't sing the song with this track because the resulting pitch is too high.

Why does the program do this? How can I fix it? Is there any way to manipulate the music to lower the pitch in Movie Maker?

Thank you.