Go into the 'Function Menu', go down to/select 'Others' this should give you 'set up' - go across to 'set up' by using the across arrow (round the OK), when it is highlighted press 'OK'. Now go down to 'Display', then across and down to 'New Channel Message' press 'OK' and you get a choice of 'Automatic' or 'Off' - highlight 'Off' and press 'OK'.
Then just press return until you are back with the TV picture.
That should switch off the message.