Exactly what are you editing (your source) and you do understand that a DVD is about 1/4 the resolution of a High Definition source file?
Photo Scaling for Video http://forums.adobe.com/thread/450798 may help
-HiRes Pictures to DVD http://forums.adobe.com/thread/1187937?tstart=0
Comparison picture of video screen sizes http://forums.adobe.com/thread/1120039
Details are lacking to answer your question. Please supply
What is your burn to:
DVD-VIDEO ISO Image
AVCHD ISO Image
Blu-ray ISO Image
Important: What preset did you select for the burn to ISO Image?
You do not want to be using burn to AVCHD or Blu-ray ISO Image unless the resulting .iso file is expected to have a file size less than 1 GB.
If you do, when the .iso file is taken to disc, the player does not recognize the format on the disc.
What was the project preset that you manually or the project automatically set for the project to match the properties of your source files?
What were the properties of the source files that you imported into the project?
Please review, consider, and supply details so that we can help you.
Any questions or need clarification, please do not hesitate to ask.