Do you remember what the error message was? Next time follow this workflow to help ensure the best quality final product and separate the encoding process from the burn process:
Once you have the project as you want it save it as a disk image via the File ➙ Save as Disk Image menu option. This will separate the encoding process from the burn process.
To check the encoding mount the disk image and launch DVD Player and play it. If it plays OK with DVD Player the encoding was good.
Then burn to disk with Disk Utility or Toast at the slowest speed available (2x-4x) to assure the best burn quality. Always use top quality media: Verbatim, Maxell or Taiyo Yuden DVD-R are the most recommended in these forums.
What was the source material used in the project, stills for a slideshow, movies, ...? Where did it come from?
It sounds like it may be an encoding or multiplexing erros. Look at this post by Bengt Wärleby on that subject: HT1645 I was burning a DVD and the...: Apple Support Communities.
The error message is the same if I save the project as a disk image.
The source is a movie made with iMovie with 6 chapters. I added photos on the panel of the iDVD project.
I made the same operations for a long time without problems with the previous projects and I don't understand this failure.
I wonder may be there are some wrong files to cancel in the library ?
Are any of the chapters in the movie at the beginning or within 2-3 seconds of any transition? That's a no-no.
Also did you edit the movie at any time after you had added it to the iDVD project. That elicits a well know iDVD problem. If the movied was edited after have been added to the project it's best to start over with an new project and add the movie to it and proceed.