same problem for me ... check out this thread
on AVSforums about it.
I have the same exact tv as you and had the same problem. I took it to a repair shop who told me I needed a new DMD chip and that it would be 850 to fix. I used the information in thread above to get the part number and bought the chip on ebay for under 200. Here is a link to the listing CHIP
People have had good success. I will be replacing mine tomorrow.