1996 Chevy Corsica CD player starts to turn on then off

1996 Chevy Corsica mileage: 91,000. About two weeks ago, I was driving home from work at about 10 pm. My car CD player starts to turn on then off. It did all the way home. I thought it could be a loose connection or something. So, the next morning I checked the CD player and the amp connections everything seemed fine. I drove to work the next day everything seemed to be ok. Then when I drove home at 10 pm again and the same thing happened. It happened like that for a week. The following week I was driving home at night and my headlights started to dim, then the radio and lights both shut off, then the both came back on. Now this cycle has been repeating itself. Now my radio doesn't stay on for more then a couple of minutes then it shuts off. If you turn the headlights, the radio automatically shuts off. I noticed that when the radio and headlights shut off my seatbelt warning light comes on, and when the seatbelt light shuts off the radio and lights come back on. Also, when the radio and headlights shut off so does the dome light if it's on at the time? This cycle repeats itself the whole time I'm driving now. My uncle thinks it might be the voltage regulator, but I have no idea what is causing the problem. Do you have any suggestions?