I am not looking for a solution for this one, just wondering if anyone else has seen it.

Just occasionally, when watching BBC1, it glitches in some way and, although it is still saying that it is on BBC1, it is actually displaying the programme content of ITV4.

A power down reset fixes it.

Yes I get that too, but usually just flipping channels corrects it.

Yes, I have had this a couple of times but not recently.

With my machine, it stayed on BBC-1 but mysteriously became Sky Sports News.

On one occasion, I rewound the buffer to the point of the change, and you could see a ghostly image of the Sky channel starting to break through (mosaic); then it became Sky Sports News.