Hi,
Due to the switchover of signals from Analogue to digital in the UK, Freeview has recently undergone a number of changes which mean that users have to
re-tune their TVs or digital boxes in order to pick up the new signal.
There is a full guide at this link where you can easily obtain the exact instructions on how to do this with
your particular TV model.
http://www.tvretune.co.uk/productmanuals/
Retuning should resolve the issue.
If you continue to have problems please ensure that all cabling to the device is secure especially any patch cabling that takes the signal directly to your TV. Digital signals are very prone to problems especially if there are loose connections, faulty cabling or shorts between the inner and outer cores of the cabling itself.
See photo below showing inner core and outer shield wiring on cables -
If your cables have screw on type connectors and are not sealed connectors make sure there is no short here causing a problem. In other words make sure B in photo has no contact with D in photo from within the connector itself.
Hope this resolves the issue. If so please do leave a vote for the solution. Alternatively if you continue to have problems post up a comment and I will be happy to respond.
Many thanks.