screeching from a LM386????
no seriously this is a finicky little PITA amp chip and if the cosmos does not align right that is a sheer fire way of letting you know. I have never personally bothered figuring it out, though I am sure others have but I have worked around it in a couple different ways, totally ghetto of course.
one was just to fiddle with a trimpot then hard wire the input divider so it would shut up, and then change the amplitude of the input.
the other oddly enough was to put a LED in parallel with the power going to the chip.
personally I hate the thing, but thats just me, and there is a real way to solve the problem, maybe someone can chime in.
depends on what you want