I had my car running today for about 10 minutes and then the starter decided to suddenly engage at idle. I was in the driver seat when it happened so I switched it off right away, but it still kept spinning. I ran to the front of the car and pulled the neg battery cable and it quit. If I touch the neg cable to the battery the starter fires and tries to start the car. It has never happened before. I am thinking it would have to be ignition switch or solenoid. Any ideas on a possible culprit?