The "Media Center" on my Windows XP computer has lost its will to show any TV. When I try to get it to scan to pick up the channels it does its pieces and reports there are no services and accuses me of not having the cable plugged in. And yet only yesterday it was showing them all right - and I've checked, and the cable that plugs in is still carrying the signals all right, because I tried it on a portable TV.

I've tried doing a "system restore" to a few days ago, but it still can't recognise any signals.

Any suggestions? Apart from "who needs TV on a PC anyway". (The answer being, it's good for saving programmes, because the only DVD recorder I have is in my computer.)