Sony Vegas rendering problem?

Here's one that I haven't quite figured out. I captured some 8mm film over the weekend. I then uploaded into Vegas 6.0d, did some color correction etc. Only 2 reels 4 minutes each.
I rendered the files separate so that my client can pick either one from the menu. When I look at the rendered MPG2 file it looks fine on both clips.

I then bring both of those clips into DVD architect. Set up the menu, and when I go to preview either clip they are very pixelated. I change my view on the preview window to best (production quality)and the pixelation is removed. When I burn my DVD I still get the pixelation. I tried to render with a 8000 CBR a two pass VBR and still pixelation.

So I decided to bypass Vegas and bring the AVI files straight into Architect and do the conversion from there. When I burnt the DVD it was fine no pixelation.

I then get the idea that I'll render out of Vegas an AVI file and bring that into Architect. Wrong answer I still get the pixelation.

So what is puzzling me is I can watch the Vegas rendered MPG2 on windows media player and it plays fine. I can bring the AVI files directly into Architect, convert there and it plays fine.

So what is going on with the correlation of rendering the MPG2 in Vegas and the pixelation that is happening when I bring those 2 files into Architect and burn the DVD.

This happended once before with 8mm film to me a few months back and I'll be darn if I can remember what I did to fix it.

Kurt