I just started to notice this issue when I got an HDTV. Basically on any 4:3 material (like TV shows, etc), it will occasionally show rows of horizontal lines across the screen, like if there is some sort of quick transition or something. I have tried all of the settings including 'Movie', 'Smart', and 'Still', they all show the problem. The 'Camera' setting seems to eliminate the problem, but adds a lot of additional artifacting in its place.

Any ideas for a way to fix this problem, or is this an inherent issue with the 520 playing back in Progressive?

It's called "combing" and is an inherent issue with the 520's deinterlacing chip (Mediamatics). It doesn't do that well with interlaced material, which often includes TV shows.

This page will help you understand what you are seeing:

http://www.hometheaterhifi.com/volum...e-10-2000.html