DVD Problem

So I converted an AVI source file on my computer to MPEG2 using SUPER (by eRightSoft). I created an ISO image and burned it to a DVD using Nero. I played it on my PS3, ran like butter. I then played it on my Phillips DVP3980, and to my dissatisfaction, found the aspect ratio to be distorted and forced into fullscreen. So I go into the setup menu, change the TV Display option to 4:3 Letterbox, then to 16:9, only to discover no changes whatsoever.