Cadillac Repair: 97 Cadillac Deville Concours Anti Theft System, cadillac deville, dashboard

Question
My 1997 Cadillac Deville Concours is reading "Anti Theft System Problem - Car may not start" on the dashboard. How do I fix this? help!!!

Answer
IS or HAS the CHECK ENGINE light ever illuminated while driving the vehicle and or has any other lights illuminated or any messages from the message display center ?.

What work or diagnostics of ANYKIND WHAT-SO-EVER have been performed on the vehicle trying to fix this problem ?.