For the past few months we have been having problems with scrambled picture on some Sky Digital Channels. The interference on the image was similar to how the picture scrambles in bad weather.
The problem only affected certain channels including True Movies (321) True Movies + 1 (322) and Brit Asia (833). All the affected channels were free to air and it only affected them some of the time. If you ever went onto an affected channel and then changed to a different channel, then the Sky Digital box would crash. The only way to fix the problem was to reset the box at the mains. We even tried a new box but the problem persisted.
Finally we found our landline phone was affecting the picture. Our landline phone is a digital phone and some how it was affecting the picture sometimes.
We have now moved the phone away from the Sky box and the problem has been fixed.
Hope this helps someone.