There are a number of issues that can cause this problem, but essentially it happens when the HDMI handshake fails. The handshake happens so that a connection between the source and your TV can be established, and a channel for the communication of you signal can form… ie you can see the picture from your film player, service provider or picture source. In my experience this is most often cable related. For example! You may have had a HDMI 1.4 (or lower) cable which worked perfectly with your older HD 1080 TV but you’ve now got a UHD TV which requires an HDMI 2.0 compatible cable (higher bandwidth for the most part) but you’ve not changed the cable. Now it may even be that the old cable actually worked perfectly for ten minutes, an hour, or even a day, then suddenly it stopped working, and you think waahh it was working fine its not the cable, but in fact it is. Without going in depth into why this happens, suffice it to say it just does. Minute variances in tolerance will cause the connection to fail when...