i have a little more info this time, this is my system: an avic d3, 4 6: door speakers, a pockrord fosgale punch p400-4 powering a 10" jl woofer in a poabox which sits snugly under my back seat. i have already changed out my 10" three times within the last year. this last time there was so much smoke i thought it was on fire. how can i fix this problem?

You already posted this topic yesterday... how do you not remember that? And if you did, why not just add tis info to that topic instead of making another topic about the same exact thing?

http://www.avic411.com/forum/viewtopic.php?t=17345

Anyway, you are either overpowering the sub, there is a short in your wiring, or it's possibly running at an impedance that's incompatible with the amplifier. What model of sub is it and what model of amplifier are you using.