When the light stays l can hit the button to lock all the doors and all the doodrs lock but the drivers door lock will lock , then unlock all by it,s self .

There are times when the light doesnt come on and everything works perfectly, what gives?

From another site with same problem---door switch is bad and needs to be replaced.go to..
http://alldata.com/techtips/2004/20040329c.html
It appears that on this model car, the switch is located inside the door on the lock mechanism.not too easy to get to.
Hope this helps, Paul

sounds like a bad door switch you can get a new one for about 6 or 8 bucks at you local parts store they are very easy to replace good luck

Check all the sensors and wiring for the security system. l had this issue on a 1998 Taurus, and it ended up being a bad connection in the drivers door to the security keypad.