This seems like the most appropriate thread to make this reply; I hope someone can help.
On my Powerbook (Al, 15", OS 10.4.6, Matshita DVD-R UJ-816 superdrive) I've got Toast 6.1.1. I've never had any issues with Toast until very recently, when I started trying to burn DVDs (DVD-R media, Verbatim) using the "DVD-Video from Video-TS" option under the Video tab. Every time I've tried, I get the following:
"The drive reported an error: Sense Key=MEDIUM ERROR Sense Code=0x73,0x03" followed by "The disk failed to be written."
Very frustrating. So as a control I moved the complete folder holding the video/audio files over to a G4 PowerMac, running OS 10.3.9, also with Toast 6.1.1 and a Pioneer DVR-109 burner. Using the same settings, I am able to burn a video-DVD no sweat. Also using the same blank media (in a couple of cases, using the very same disk rejected by the Powerbook!).
The Powerbook Superdrive seems otherwise to be healthy; it records and plays CDs; it recognizes and plays DVDs. It records a data DVD just fine. However, attempting the workaround suggested elsewhere of making a disk image and then copying that to DVD resulted in a slew of error messages (among which were several reported here; my apologies I didn't write them down at the time).
I've repaired permissions, used Disk Warrior and Disk Utility, even brought the 'book to the local Apple Store. The only suggestion the guy there had was to upgrade to 10.4.7 and/or upgrade to Toast 7 but after reading many of the posts here I am leery of doing the Toast upgrade, and I can't imagine how/why the OS upgrade would make a difference. (Especially as 6.1.1 is behaving perfectly on the PowerMac.)