I have been using a radio transmitter to listen to my ipod in the car. The crap came apart without me noticing and a nice piece of metal was lying in the 12V hole starting to heat up. After a while smoke was coming out of the ventilation and the 12V hole was shining orange. Turned off car, removed the garbage and all was fine except the fuses went.

I tried replacing the fuses (interior lights + posterior, and tail) but sparks are flying when inserting new ones and they immediately burn off.

What could cause this annoying behavior? Not sure where to start.