LCD TV problems
This is called "Vertical Banding", you need to adjust your horizontal position/size screen settings, if the lines disappear you're ok. If it stays there you may have a defective screen. If you decide to send it back, I suggest the Sony Bravia 42" LCD HD 1080p, it has the best customer ratings in the states. My Dad just bought one and what a difference from Samsung or Pioneer!!
http://www.sony.co.uk/bravia
http://www.sony.co.uk/bravia