NeroVision Express 3 Encoding Problem!

Hi everyone! I ripped my Star Wars Trilogy dvds using Nero Recode into AVC mp4. The resolution of one of my movies reads as 704x288 when I play it in Nero Showtime and plays as a widescreen movie like the original. When I try to put it back onto a dvd using NeroVision Express 3, the movie gets stretched in weird ways whether I use 4:3 or 16:9. If anyone can give me some tips on how to burn it back onto a dvd with its same widescreen aspect ratio it would be much appreciated. Thanks.