Downstairs I have an older Tivo box which is absolutely fine. Upstairs we have a V+ HD box and for a month or two now many of the channels develop symptoms of poor signal after 10-20 minutes watching.
Oftentimes the channels are fine at first, but after some time it starts to get a bit choppy and the audio cuts in and out with it. I've tried live, recorded and on-demand viewing and I get the same thing. I don't get any problems with Chromecast or the Blu Ray player on the same TV, so I'm confident it's Virgin related.
As a side note, the box itself has developed an annoying very high pitched tone which I didn't have before. It goes away after a few minutes of the box being switched off which makes me think it's likely the hard drive.
Perhaps the box is on it's way out, causing the first problem, but I'm not sure.
I would like to arrange for a technician to take a look at this for you so I'm just going to send you another message which you will find if you click on the purple envelope at the top right of the screen.