Incorrect Aspect Ratio CHS 345HDC

[#1]

     I am having a problem with a new HDTV I just bought (Sony KDL55W900A) and I believe it has something to do with the signal coming from the STB.  I cannot get a full screen image from the STB unless the Screen mode on the TV is set to "Full".  Sadly, I wouId rather not use the "Full" option because this stretches the image causing distortions.  I would much rather use the "Normal" setting which I used for the Screen setting for my Blu-Ray player.

     In the Video Setting menu, I have set the STB (CHS 345HDC) to output 1080i as well as the "Native" option.  I have the STB set to 16:9.  This results in a rather compressed image in 4:3.  I can stretch the image with the "Full" screen setting on my TV, but I noticed that this introduces artifacts in the picture and is not a true HD signal.

     Just to get the obvious iut of the way, I have tried two different HDMI cords and the original component cables I got from the instilllation.

     Is there a way to get the STB to output a full HD signal so I do not have to stretch the image?