If the reception for the TV channel that is being shown disappears then the picture will freeze. Shortly after this a message appears informing that the reception has been lost for the current TV channel, and a new search for the channel continues. When the reception returns the display of the TV channel starts immediately. It is possible to change channel at any time when the message is shown.
If the message No reception is shown then this is because the system has detected that there is no reception for all TV channels. One possible reason may be that a border has been crossed and that the system is set to the wrong country. In which case, change to the right country in accordance with Searching TV channels/Preset list.