The Vobulator is the Sonic AuthorCore module, that does the layout for the DVD and creates the structure of the VIDEO_TS folder, the IFO, BUP and VOB (hence its name).
My guess is that there is something wrong in the inteneded structure of the Project. It could be something simple, such as a Stop Marker accidentally placed at the end of the Timeline, or something else.
Can you give us the complete details of your Project?
Yes, Bill, it was a stop marker at the end of the project. Thank you. I removed it and now it is OK. But - still - it worked well in PrE8.
Great news! That has caused a lot of folk problems, and often with the error message, that you got, though not always.
Good luck and happy editing. If all tests OK, you can mark this one "Answered" for others to use, in the same circumstances.
Done! Thanks Bill.