Audio Systems: car radio display, ford taurus, annoying problem

Question
I have a '98 ford taurus SE. I just noticed that the radio (original one) display is not working when I turn the ignition on. The radio displays fine, however, if I turn on the headlights. The radio is working fine in every other respect. It's just a small annoying problem. Do you have any idea what the problem might be?

Answer
seems somehow radio is wired to lights instead of it's owm source. sure there is a wire that should go to headlights so when lights on, it dims radio display, but main radio should not be wired there. i'd find auto sound installer; shouldn't take more than a few minutes to correct....