I've recently bought a new Sony Bravia KD49XF7003BU, and I'm having a bit of a problem with the HD Channels.

Upon the first setup, the HD channels worked fine, no problems at all. However, whilst watching a HD Channel I turned on my PS4, and the HD Channel suddenly lost signal. I subsequently re-tuned the telly and the channels had completely vanished. 

After re-tuning several times, trying to blank tune the channels etc, I finally got the channels back, but the next day they vanished again. 

My signal strength is also weak considering I'm in London, I'm getting around 68/100 strength. So I've narrowed it down to two options:

1) My HDMI cable is interfering with the signal

2) There is a problem with my aerial resulting in weak signal, meaning the tuner is struggling to find the channels.

3) It's both.

So I've changed the HDMI cable to the PS4, but the TV still can't find the HD Channels. So it's hard to say if this has had an effect.

Other things to note, if I touch the Aerial cable at all, the signal diminishes on the tv, the slightest movement of the cable effects the picture quality.

Has anyone else had a similar problem, and is there anything I can do to remedy this?