Possibly needs servicing
Hey there, here's the thing: provided this green line is happening on multiple sources (e.g., DVD, Cable, etc.), you'll need to get the TV serviced. If it's not happening on multiple, then it means there's an issues between whichever one device and your TV. So be sure to check more than one source if you haven't.
Now if you need service, here's the link to the thread we've written up giving you your options on how to setup service: http://forums.cnet.com/7723-13973_102-542437/service-issues-click-here-for-help/
I hope that helps. If you need anything else, drop us a line here.
-- HD Tech