What are you editing?
Importing Video http://forums.adobe.com/thread/1065281
-and project settings http://forums.adobe.com/thread/1112086
What are your share settings?
Saving & Sharing http://forums.adobe.com/thread/1137128
-Sharing to DVD or BluRay http://forums.adobe.com/thread/1137645
-Sharing for Movies http://forums.adobe.com/thread/1051093
-Sharing for Computer http://forums.adobe.com/thread/1058237
There are several considerations that go into trying to analyze the situation.
1. What are your source media for the project?
a. If 1920 x 1080, you may be seeing the difference is formats...the 1920 x 1080 frame size compared to the 720 x 480 frame size (NTSC). Whether you use DVD-VIDEO Standard or Widescreen, the frame size is going to be 720 x 480. The Widescreen will have a 16:9 flag to stretch the video for display after encoding.
b. If photos, what are the pixel dimensions of the photos and how many?
2. Another factor may relate to what is called Field Order (relates to interlaced video). If you have source media/videos with Field Order of Upper Field First, that probably has to be changed to Lower Field First to meet the specifications for DVD-VIDEO, that is, Field Order Lower Field First. That switch can be made by using one of the special Hard Disk Flash Memory Camcorders project presets or using the regular project preset and then apply Field Options/Reverse Field Dominance to the video at the Timeline Level. Also, if flicker is involved, Premiere Elements has anti-flicker that can be applied to the video.
3. What does the video look like from the rendered Timeline before you apply menus and burn to disc? And, what is your player for the DVD-VIDEO/TV screen size? Also, in what specific ways is the video quality diminished?
Let us start here, check out the above, and then decide what next.