When you are in the guide, the highlighted channel is the fourth of the seven displayed. When you press the up button, it does nudge up a line at a time, but the highlighted channel is still the fourth of the seven displayed. This behaviour continues until the highlighted channel is CH4, then further up button presses move the highlighted channel line to itv, BBC TWO, then BBC ONE. The next up button press takes you to the highest channel number at the bottom of the screen. Three more up button presses take the highlighted channel to the middle of the guide (line 4), then further presses nudge up a line at a time with the highlighted channel remaining the fourth of seven displayed.