problem syncing music from iPhoto to iDVD

I created a slide show in iPhoto (iLife 08). I created background music in Garage band by linking existing songs together. This is the background music I used for the slideshow. I timed the slides and music to match. Everything played exactly right when I viewed the slideshow. When I sent it to iDVD, the music was no longer synced. 15 minutes into the slide show, the music was off by over 25 seconds. I tried exporting the slide show to Quick time, but the same problem was there. I tried converting the music to AIFF, but that did not help. Any ideas? Thanks