I turned my Samsung TV on this morning and all of my Virgin HD cable channels, which I have running into the HDMI port, are just a black screen. I can pull up the menu, navigate through the programme guide and settings menus of the box but no channels actually show anything.

I then tried the PlayStation 4 and the same thing, just a blank screen.

Any suggestions on what might be the problem? I'd have said the HDMI port itself but given I can see the menus on there I'm at a loss.

are you using the same cable? do you have another you can plug into the virgin box to test?

Different cable, same result. I'm getting a "Not Supported Mode" error on the screen when I try the PS4, which works fine when I plug into a different monitor (so I know it's not the PS4).

Update: I tried the Apple TV and that works absolutely fine. Now I really am at a loss.

Edit: The Apple TV gave me this error when I tried to watch a video.

This content requires HDCP for playback. Either your HDMI cable isn't properly connected or your HDMI connection doesn't support HDCP. Please reconnect the HDMI cable from your Apple TV and try again.

(I'm using a third, different HDMI cable so I know it isn't the cable).

Since everything you plug into the telly gives a blank screen it kind of suggests the telly is the problem. If it has more than one HDMI input try all of them just to see if that makes any difference. Also put everything into standby then turn the TV on first then the external box. It might be that the order you turn things on screws up the HDCP handshaking.

If all inputs are the same and the turn on order has no effect the next thing to try is to look through the menu system to see if there is some HDMI setting that turns HDCP on or off, can't say I've ever come across such a setting on the various TVs I've mucked about with but you never know.

Failing that try doing a "factory reset" on the TV. It may call it something else, like "default settings" or similar. This should reset the TV back to it's "out of the box" state so you'll have to go through the initial set-up again. But if it is some odd settings error that might clear it.

And of course it could be a hardware problem in the TV.

Turn all the equipment off then on again. It's an HDMI handshaking issue.

Ok, since posting I've tried countless suggestions. When I connect my Virign box to the TV through HDMI, if I put the box in and out of standby, I get a picture but no sound. Change channel and I lose the picture. In and out of standby again brings the picture back but still no sound. Progress, but not much.

Check the audio settings. If there is a choice of audio formats over HDMI set it to PCM or LPCM or Stereo depending on how it is described. If it is set to some surround format the TV may not know how to deal with it. Plain vanilla PCM Stereo should be OK however.