Try adjusting the AutoMotion Plus feature to "Smooth" or "Off".
Does that help?
Just bought a samsung 46' 600 LCD TV, and connected to Camcast cable box. For some TV shows, I noticed apparent picture shaking every 5-10 seconds. However, when I connect the same signal to my 32' samsung LCD, there is no such a problem. Wondering what to do and if I should request for a replacement.