Sounds like a connection issue. A tech would try unplug, plugging internal things as a first response. I know some think this is planned and it is. Long ago makers would go for 10 year designs. As the consumer balked on cost, some makers dropped to 7 and then 5 and there are significant cost reductions you can get. Most sets will get more, some will get less but a consumer does not want to discuss design and cost trade offs.
Ask a TV Tech to take a look.
Have a problem with my lg 42 lh3000 have had for 4 years now ,but now once in a while half to a quarter of the screen fades to black sometimes will clear after 10 mins. and sometimes if I rub screen gently will clear.I thought 10 years for such an expensive tv or is this a classic example of planned obsolescence?