Dash Light Parking Light Fuse

Hey guys I was driving on new years and my dash lights went out all of a sudden and it also kicked off my tail lights. So I figured it was the fuse. I replaced it and the fuse blew out instantly as I turned my headlights on. Then I put another fuse and dimmed my dash lights and the fuse lasted longer but eventually blew out. So now I am stuck as to why the fuse is blowing? It has never done this before. I own a 96 GMC Sierra any suggestions would be great.

Ok well it seemed alot of people were having this problem but the problem is fixed. Apparently on Chevy's and GMC's something messes up in the wiring after a few years. Anyway the NEGATIVE (black) wire on the radio turns positive when you turn your lights on causing the fuse to blow. So what you do is wire the negative wire to some heavy metal on the truck (seat, under dash, door jam) somewhere like that so you get a good negative connection. I saw alot of people saying that after they wired a new stereo the dash lights and tail lights went out. So anyway yeah just cut the black wire to the radio and wire the radio to another source of ground. Fixes the problem right up and you can drive at night while "bumpin" the truck with your new cd player! w00t