The power button can learn macros, and it sounds like your power button has been taught one. To erase the macro, press "AUD" and "MUTE" at once, then press the "POWER" button to select that button, then press "CHANNEL UP" to erase the macro on the power button. That should hopefully get you back on track.

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gonk -- Saloon Links | Pre/Pro Comparison Chart | 950 Review