Security system not working properly

We have a 2001 Grand Am SE and a few weeks ago I was driving to work and the door locks started making a noise as if someone was sitting there hitting the lock/unlock button repeatedly. Then, when you try to unlock the doors using the power switch, they won't unlock. You have to manually unlock each door or use the button on the remote. Sometimes when you get out of the car and go to push the lock button on the remote it doesn't sound the horn. Also, EVERY time we put the car in park, the horn sounds as if we hit the lock button on the remote. Get what i'm saying here? Around the same time all this started, the security light will stay on as long as the car is on. Shortly before all this started to happen, he re-installed his speaker box and put in some little neon lights in the car. He says this has nothing to do with it but everytime he installs something, something goes wrong shortly after. Just wondered if anyone is having this problem or has had it or knows any ideas of how to check what it is. Thanks for any help!