Novice's DVD Burning Question

Archived from groups: rec.video.desktop (More info?)

I recently got a new PowerMac G5, and it comes loaded with iDVD 4.
Yesterday, I tried to burn an 18-minute, Final Cut 4-edited video on
to a DVD with iDVD, and I had many problems with segments of audio
being lost and this weird cube-like pixelation thing happening at
several points, particularly at transitions.
Can anyone suggest what might be happening to create these problems?
I would appreciate any insights.
Thanks, Neil