This is why I intend to buy a plasma.
My understanding is that LCDs have issues with their refresh rates, which is why you have the dynamic motion or 120Hz/240Hz feature. This involves frame interpolation, which basically "fills in the blanks" in what, to me, looks EXTREMELY unnatural.
My dad's in the market for a new TV so I took him to a local home theater store yesterday. We were watching a Samsung LCD -- one of last year's B650s. It had 120Hz, and they were playing an SD DVD of Vantage Point. Lots of action on the screen, etc. To me, it looked.....weird. Almost too perfect or too smooth. That's when I figured out it was the motion interpolation. I gather the 240Hz sets smooth this out better so it doesn't look as unnatural, but this is all designed to fix the motion blur that older LCDs have, and as a result, it took things in a wacky direction that makes it look like....I dunno...video tape? Like everything's too....steady? Something like that. It's hard to describe but to me it just looks unnatural.
My dad, however, couldn't really see the difference. The store guys flipped the station to the Olympics, however, and those looked just fine.
So, basically, yeah, try knocking down the motion interpolation feature or at least reducing it and see if that helps. Or buy a plasma. I hear they don't have this issue. They may have OTHER issues, but not this one.