I have a Sharp LC-42D62U. The other day I was trying to attach some external speakers to the output audio jacks in the back and couldn't get them to work. I tried to change the menu option ( audio fixed to audio variable ) but it wouldn't let me. I then noticed other options wouldn't change either like ( advanced in display menu) Most of the menu buttons wont change. I can change the Audio Equalizer ( bass, treble etc) and the Display ( color, brightness, etc) I use to be able to change things in the advanced display menu. OPC is off. Is there a setting somewhere blocking me from making changes? I use Input 1 hooked up to a Eastlink DVR. Does anyone have any suggestions? I would really appreciate any help. Thanks