I am getting the same problem, just started since I installed the new iTunes, I burned a DVD the day before with no problems at all, and that was the only change, however the DVD was a different one, the one that worked only was a slideshow, this one had a movie file (that took forever and a day to encode the audio for... well, only 4 hours to encode an hour of audio from a QT movie?!?!?)
Note: I always burn to a .img file first, the comptuer I use iDVD on does not have a superdrive, so I burn to an image, then move the data using an external HD to my older one with the superdrive. It spent hours encoding, then spat out that error, went unresponsive for an hour (waited that long before I finallly killed it using activity monitor) and no .img file
