Sometimes i get a screen message saying: no signal being recieved, or sometimes, there is a technical problem with this channel.
this used to only be when the weather was poor but its happening more now.
I had the same problem, and also I was unable to receive some of the ITV regions ( STV, UTV, Grampian and Channel ). It turned out that the satellite dish was not correctly aligned. But since it was sorted, there have been no problems. That could be why you are experiencing similar problems.
Don't call Sky as they cost £60 to come out and fix it, some may tell you it's something else. One told us we need a new box as it was broken, in the end i called my mate who know's a bit about Sky etc and he said nudge it with a broom stick and now it's back and works fine.