It might not even be possible to fix it on 480p... Not enough horizontal pixels. Comparing 480 pixels to 1080, (not sure on horizontal, but it's a big difference).

The issue has to do with interlacing, scaling, and overscan. Sounds like when you move it to close to the edge the game things it's off screen and defaults it back onto the screen. Might have just run out of space.

No offense though, 480p is dead tech.... You should really upgrade to 1080p... Unless you have some HUGE 60" 480p Big Screen TV I see no reason why you wouldn't upgrade. You can pick up a 40" 1080p t.v. now days for less than $400...