Why is the preview for my video in Windows Movie Maker Completely black?

I installed the Divx codec and the Xvid codec and I am able to view the video in both Windows Media Player and Windows Movie Maker if I click on the clip and preview it but if I drag it on to the time line on Windows Movie Maker and preview it on the time line it doesn't play. Well the audio plays but not the video. Does anyone know what is wrong/how I can fix this. BTW I have Windows Movie Maker for Windows XP if that helps.