Originally Posted by sse for me
how does the chip on your key look. mine was doing that and not starting sometimes also. the chip was worn and went to dealer got a new key cut problem gone. key is like $15.00 cut :o :o :o :o
Ace Hardware can do the keys as well. They have a thing called a VATS Interrogator that tells them which of the 15 possible resistor values is in your key, and that tells them which blank to use.
As for the Security light, it blinks while the door is open with the car off as a reminder to you to lock the car. It should _not_ blink at you or come on steadily while driving. I forget the details offhand but I think blinking indicates a fault detected in the system (e.g. bad trunk lock switch); a steady light means a break in the detection circuit through the chip in the key, such as from using a dirty key.
As I said before, it has to be a really dirty key that breaks the connection for 60 continuous seconds before you get the solid fault light going on, and even then the car isn't going to suddenly shut down on you, but at startup time it will need the connection through the key to last long enough to _start_ the car in the first place.