Before we get into inspecting your Timeline content as a whole and parts thereof, let us start with
a. Do you have menu markers in the project's Timeline? If yes, did you use any stop markers? If yes, did you position a stop marker at the end of the last item on the Timeline?
If yes, then we have our answer. Stop marker is not needed there and causes problems and failures when there.
If none of the above applies to your situation, then we need to dig into the details of your project
Premiere Elements 9.0/9.0.1 on what computer operating system? And, are you working with the 9.0.1 Update version?
What is your project preset?
What are the properties of what you put on the Timeline? And what does the Timeline content consist of? If you did use menu markers, have you checked the spacing between them on the Timeline so that you do not have any markers sitting on one another? What disc menu did you use...any overlap of buttons seen when you were in the disc menus section of the program?
In the burn dialog (with DVD disc in DVD burner tray), what is displayed for in the Quality Area for Space Required and Bitrate (with check mark next to Fit Content to Available Space)?
Let us start here.
Any questions or if clarification on anything written is needed, please do not hesitate to ask.