Lock the screen and keyboard
If you want to carry your N800 or N810 in a pocket or bag, it's a good idea to deactivate the touchscreen and keys so they don't accidentally get pressed.
How to lock and unlock the screen and keys on the N810
To lock the N810, simply push and hold the dedicated lock switch for a second, then let it spring back into place. To unlock it just repeat this same procedure.
Incidentally, a locked touchscreen will automatically unlock when you open the N810's built-in keyboard, and then automatically relock when you close the keyboard. An unlocked touchscreen isn't affected by opening or closing the keyboard.
How to lock and unlock the screen and keys on the N800
To lock, press the power button very briefly, and this should bring up a menu of various options. Select the option to lock the screen and keys.
To unlock, press the power button again very briefly, then press the direction pad button (aka the rocker key).