Constantly losing reception of main channels, retune but does not find them?

[werlynne]

I have also posted this in error on the Freeview receiver forum, my kit is a Recorder.
I am having problems with my Humax, it displays TV fine but suddenly it looses many of the main ITV/Ch4/5 channels, not ITV4. I get the Black screen with a standard message, "The channel is scrambled and not available " which after a few seconds changes to "No programmes are currently being broadcast on this channel" The I button shows the programme details. If I retune it is unable to find them, they do not show up on the EPG, then suddenly maybe a few days later I do another retune and have reappeared and work fine. Things stay ok for a few days and then the problem is back again.
I have other TV's which have Freeview and are working fine on all channels, the problem seems to be only with the Humax associated TV.
I live in Manchester and are having plenty of rain at the moment but this should not effect anything and the Freeview Direct TV's are working fine.
Has anyone got any ideas?
Many Thanks
Update, I have looked again 30 mins later and now rather than just the Black screen it is sort of trying to show some picture, predominantly black with some squares of a colour picture.

 

[Ezra Pound]

Are the 'working' TVs being fed from the same aerial? You could try disconnecting the aerial input feeding your Humax to the TV display used to display the Humax's output to see how it copes when fed by the same signal

 

[werlynne]

Yes it is the same aerial........

 

[Black Hole]

The only option you have is to try performing a full re-initialisation: Menu >> Settings >> Installation >> Factory Default. This will clear out all settings and require setting up all over again (including your recording schedule), but will not remove your existing recordings (unless you perform a disk format as well).