97 keeps blowing park light fuses

Help. Im a newbie with a car thats going crazy. I had a new stereo installed and my park lights went out and every fuse put in, blows within seconds. But when the radio was unhooked, the lights worked again.So i had the radio professionally hooked up,thinking it was a wire crossed or grounded.after the 2nd install they worked for a few hours, but my park lights are out again.

possibly a wire on the radio or the wiring harness is grounding out!!

What is happening is that when they hook up the new stereo, there is no ground wire that connects up with the factory connector. So what they do is install the ground wire to the illumination wire and every time you turn on your lights, you blow a fuse because you have an overload in your park light/illumination circuit