Went to the movies tonight. Came out and my 1999 F150 would not start. Got the "Theft" light on the dash. Engine turns over but no start. I have only the 2 original keys. I got a ride home then went back with my second key. Same story. Why would the SecuriLock system think that my keys are no longer valid? What could fail causing this scenario? Is there a simple way to get this all back working? I am puzzled. I do not have any remote starter or any bypass. This is all just like it was when I drove it off the showroom, well older and uglier but you know what I mean. Thanks for your help.