360 box unresponsive

A few weeks ago, when I changed channels, the screen went black. None of the buttons  on the remote would do anything although the light on the front of the box would flash. The only button that did anything was the power button that would turn the box light red but then wouldn't come on again. The only thing to do was to power off the box by the switch on the back and reboot. This happened a few times and so I rang virgin. They sent an engineer out who said the box was probably faulty so replaced it. All ok for about a week and this one has started to do it. I then thought it may be a different issue with the tv or something until a neighbour said his had done this as well.

Has anyone else experienced this before I call virgin again.