Stereo quit working, and then car quit working
 

I have an '08 Mini Cooper. I was driving down the road and my stereo quit working suddenly. The next morning I got in my car and it was working. That happened 4 days ago. Then last night I got in my car and it wouldn't start. I called a friend to get a ride, and as I was waiting and calling another friend to ask what he thought the problem was, I tried to start the car and it started, so I drove home and as I was driving, my stereo quit again. As soon as I got home, I turned the car off and then immediately turned it back on and the stereo was working.

Any suggestions on what the problem is? I'm not sure if the problems are related, but thought I should include both.

sounds like a bad connection , did you check battery terminals for corrosion? loose ?