I have green lines going thru my 56 inch DLP Samsung TV. If I unplug the TV wait a few minutes then turn it back on it will be ok for 3 hours then the lines appear agin. Any thoughts on what is going on? we thought at first is was the HD converter box as this was only happening on the cabel channels. The cable company gave us a new box and it is still happening but this time on all channels including HD channels.