I have just got a samsung LE32M86BD Hd Tv and I am experiencing wavy lines over the screen when watching, it is normally on darker colours, I am also getting it when playing on my xbox 360 even though it is run through a component lead.
With the XBOX connected disconnect the aerial input and see if the lines disappear. If so try replacing the coaxial cable with double screened satellite type particularly if a coaxial wall socket in use.