iDVD ejects disk before burn is complete

I am attempting to burn a large combined video and data DVD project (6.8 GB), and encountering a problem in which iDVD ejects the disk from the drive just BEFORE the burn reaches completion. The progress bar just sits there at 100% saying that its last task is done, but never actually indicates completion (even if I wait several hours). The only way out is to hit the Cancel button.

I have tried burning both in Best Quality and in Profession Quality Encoding -- both exhibit the same problem. Burning to a disk image completes successfully, but iDVD warns that disks burned from such an image will not work correctly in some players, so it is not useful to me.

As for the DVD produced, the video content is corrupted -- some parts play, but others just get stuck, or worse yet, hang the player. The DVD-ROM data contents seem to be there in the directory -- but the files are corrupted, apparently having never actually been written to the disk.

The drive in use is the one which shipped with this MacPro1,1 (PIONEER DVD-RW DVR-112D). The target disk is a Memorex DVD+R DL. iDVD version 7.0.3 (1110).

I hope someone out there can help, as my project is already overdue...

Thanks in advance,

Josh

Message was edited by: spidey3