Ok, I have a couple more things for you to try.
On your DIrecTV Remote, I want you to select Menu. Go to Parental, Favs, and System Setup. You should see a tab labeled HDTV. Select this feature. Within this menu, you can set your TV aspect ratio, and the default Screen Format. Your DirecTV manual will explain these options on pages 77 and 78. (YOUR DIRECTV MANUAL)
If this doesn't work:
Using your TV remote, locate the Zoom button (towards the bottom). Typically this feature only applies to the actual DVD playback, but I want you to press this button and see if it adjusts the picture at all, just to be sure.
Now, if that hasn't resolved your problem, press the View Mode button (towards the top) to toggle between the TV's aspects again.
There are four parts to getting this to work:
1. Set TV format to 16:9. (Completed)
2. Set DirecTV format to 16:9
3. Adjust TV View Mode (Stretch may be your best choice, since your receiver is not HD)
4. Adjust Screen Format on DirecTV. (Set this in Menu options, then use Format button to adjust while watching programming.
Take the steps to adjust the items mentioned above, it has to be one or more of these things causing your augmented picture.