As well as other things that can cause this problem, have you tried resetting the logic circuitry by taking the battery out for a minute or so?
also when you take the battery out and then reinstall it do "NOT" switch the camcorder on, just press the eject button, as doing that by-passes any suspect commands from a sensor.
Also as you say it hasn't been used for months make sure the camcorder isn't located anywhere cold, it has to be at room temperature or the condensation sensor might take control.
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