UPDATE:
We have had an official statement from Sky on the issue.
"We are unaware of any specific concerns about any of the HD channels on Sky. However, if customers do experience problems, they can always check their signal levels to ensure the strength is good and then reboot their set-top box if required."
Sky tracks and automatically updates any channel changes, which is why the company says there shouldn't be an issue.
Nevertheless any problems should be solved by a reboot. If this still doesn't work, customers are advised to call Sky.
Published 06.06.11:
The BBC has made a change to the way it broadcasts BBC HD and BBC One HD – and left some people unable to view the channels.
An upgrade to the transponder that sends satellite TV broadcasts has seen many Freesat users reporting a loss of pictures.
Furthermore, older satellite boxes may be completely unable to receive HD channels if they're incapable of receiving a DVB-S2 signal.
The BBC recommends turning your box off and on and, if necessary, performing a retune or reinstallation of your channels.
Despite this many viewers are reporting their boxes are still without BBC HD and BBC One HD after following these steps.
The change should only affect customers with Freesat tuners, whether in digital TV boxes or televisions, including products from the likes of Humax and Panasonic.
However users on the whathifi.com Forums are reporting problems with Virgin Media HD and Sky+ HD boxes.
There is further information on the change on the BBC blog while you can head to the Freesat website for help retuning your box.
Let us know in the comments section below or on our Forums if you have been experiencing any problems.