It depends on your source files.
What type of camcorder is your video coming from and how did you get it into your computer?
Also, what Premiere Elements project presets are you using?
What are your source files? This can easily happen with GOP formats/CODEC's, like MPEG.
Your source files will often dictate what one ends up with, when editing.
The more details, the better. This ARTICLE will give you some background, plus tell you how to obtain the details of your files.
Good luck, and we'll be looking for those details,
The files were m2ts avchd lite from my Panasonic fz35 still camera. I used the hdv 720p/30fps preset.
Unfortunately, video from still cameras almost never works in Premiere Elements.
The FAQs to the right of this forum offer suggestions for converting it to a more standard DV-AVI.