Alright, I tried double and triple checking the project settings and burned the DVD again, with the same results. Here are the project settings:
I'm at a total loss.
I will now try what John recommended, though I don't see how that will change because the menu I used I COPIED directly from the stock encore menu library, edited in photoshop and saved back into the Encore library under a different name (as I've always done with ALL previous HD menu's with perfect results. The ONLY difference here being it's SD instead of HD) and the whole project comes out cropped on all four sides.... so I see no way that it could be an issue on the Premiere side of things.
I'll still try it though because I'm completely at a loss......