Maybe it's the HDMI connection. This happened to me last week with an intermittent signal. My Sharp lcd tv has its patch bay towards the top of the set. It seems the weight of the cable worked the connection loose. Now, every couple of days I reinforce the connection by hand.
All this is a way of saying that the HDMI termination is ill-thought. The big corporations in Japan, Korea, and China designed it for security purposes first, consumer convenience second. Really, they could have done a better job. I think it stinks, but it's a reality