2003 Mitsubishi Montero Sport safety switch

Vehicle has 39k miles, and suddenly today I couln't shut the ignition off. The veh will shut off, but I can't get the key to go past 'acc'. I believe it has something to do with switching in the gear box, as a couple of times while raking the shifter from park to low and back with no results, the button on the shifter would hang up. I looked for anything unusual in the linkage and found nothing. If there is a safety switch that I need to check, my biggest problem is locating it. Thanks in advance for any help.
Woody Young
San Antonio, Tx.

Reply to oldwrench: Vehicle has a floor shifter. This is most likely a problem with the interlock that prevents removal of the key unless the vehicle is in PARK. Column shift or floor?Car Repair Talk's forum.