On Tuesday, 24 July 2012, the frequencies used for Freeview|HD will change. This is only the case for terrestrial Freeview.
The changes do not affect viewers using Sky, Telstra Clear cable, Freeview satellite or those not yet watching digital television – only those using Freeview|HD®.
This will mean that come the 24th, terrestrial freeview users will need to retune their decoders or televisions.
The reason for this is to make sure that the bandwidth is being used as efficiently as possible.