Video Stretches when Exporting

[allhorrormovies]

I normally shoot with the DVX's letterbox format with the camera. However, when I export back to tape from Avid, I send it to my sony TRV38, which I only use for digitizing and exporting back. Then, the footage plays fine, but when I redigitize the footage it stretches the letterbox to look as if it were shot in 2.35. I had moved the footage to Final Cut when I did this. Does anyone know what I can do to keep the video from stretching?

Thanks
Ken