Sorry, I told you wrong.
I reviewed the user's manual myself after you responded. And after looking it over, you clearly don't have that feature on this device, because it wasn't added to all TVs until 2009 and you have a 2007 model. I had received that the assurance that it did have it, but I didn't verify that information myself before I forwarded the information on to you. So I apologize; I messed up.
Without a doubt, however, you will need the TV serviced if you want to continue using it. I'm providing the link again to the service thread for CNET: http://forums.cnet.com/7723-13973_102-542437/service-issues-click-here-for-help/
And if you decide to send in the service request, and you want me to handle it, just ask for me; it'll get assigned over to me.
Have a great day!
-- HD Tech