I am having the exact same problem:
I am a grade 12 high school student having significant difficulties burning a DVD on a G5 Mac with iDVD 5. Dispite having worked with apple computers for 4 years at the school, I am at a loss of how to correct it. This is the first time an apple product has let me down like this.
The iDVD project itself is massive – which could be a contributing factor to the problem. 5.1 Gigs onto the DVD+R set to best quality and background encoding disabled. There is over 2 Hours of video and 1200 still images. This is quite a large project for iDVD to handle I know, but since it is a school project we do not have the means at our disposal for better software.
The situation is that I set the burn to run over night, and when I come into the lab in the morning the DVD has popped out of the computer, apparently complete. The screen reports that recording is finished, but clearly from a visual perspective the DVD has not been burned (nor when I put it into a DVD player). The program also locks up at this point.
I have the computer home with me now (the school is quite generous, and wants to see this project successful), and am attempting to burn again, after purging encoded assests. If this fails, does anyone have suggestions of how this could be fixed?
Thanks very much in advance for any help you can provide! I will also post here with an answer if I am able to find one.