Lately I've had a weird issue with the starter. I'm getting a grinding noise when I release the key upon starting and worse yet a couple of times the car started and the starter wouldn't disengage. I turned off the ignition and the car was still running and the starter still engaged! I could even pull out the key. Only when I turned the key to 'start' and then 'off' could I stop it.

Should I be looking at cleaning the ignition switch contacts or the starter motor itself?