Engine won't shut off

My 1996 Lumina APV won't shut off. I turn the key and remove it and it still runs. Battery is disconnected. If i turn the head lights on with the battery disconnected it will shut the motor down. Any suggestions?

THe ignition switch has gone haywire......or do you have a remote start installed ?
BTW, battery disconnect with engine running can generate a voltage spike that can ruin the computer. I've seen it happen to a friend with a different car make though. It depends on the voltage regulator caractheristics....but that is scary.