N_Cook forklarede den 08-12-2012:
DVD player that stopped responding to the front panel buttons.
I pressed the "key lock" button on the r/c and normal service resumed.
This is a player , not recorder , why a key lock function?
Owner is a highly respected silicon foundryman with IBM

Perhaps the keylock is to prevent customers to stop the DVD-player
playing annyoing "infomercials" playing in supermarkets and malls.

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Husk kørelys bagpå, hvis din bilfabrikant har taget den idiotiske
beslutning at undlade det.