What are the yellow lines on my HDTV Projection 55 inch?

Question

My 55 inch Projection HDTV has some yellow discoloration. It's kind of like a yellow outline around everything. It just started recently, just curious if anyone knows what may cause this? I'm hoping it won't be too expensive to fix, as this TV is only 4 years old (it's a Philips if that matters). Thanks for your input!

Answer 1

color target is off