Can't access hidden service menu

I'm trying to access the hidden service menu as follows:
Menu->Settings->System->System Information...RED GREEN YELLOW BLUE GREEN YELLOW BLUE

...but as soon as I press any of the colour buttons (while looking at the System Information screen) a "No Entry" sign appears on the top right and I can't go any further.
I've tried power cycling but it didn't help.
Any ideas??

Black Hole

May contain traces of nut
Any ideas??
What could cause you to fail to access the hidden menu, despite pressing the relevant buttons in the right order, is the button press not actually making contact and transmitting anything. Once out of sequence, you have to start again.

Check the PVR button on the handset lights up for each button press.