Connection to controller - cannot display content

[rhambri1]

I've inherited a Sony 65 inch TV.

I keep getting whilst watching Freeview tv a dialogue appearing in the bottom RHS of the screen saying 'Connection to controller cannot display content' preceded with a yellow triangle with an exclamation mark inside.

I've done a full factory reset, but for the life of me I cannot find a reason why this warning pops up sometimes every 5 mins or so.

The TV is a Sony KD-65XG7073

Any solutions or ideas? I've looked through the menus but cannot see anything obvious to toggle on/off.