Today I was driving my 93 Bonneville home (going about 45 MPH) and the security light came on in the dash out of nowhere! The car is an SE and is 100% stock. It'* the most basic a Bonneville can get. It did not even come with a factory keyless entry system, nor has one been added. The power door locks still work fine and the car starts without any issues. The check engine light did not come on.

Does anyone have any ideas or seen this happen before?? :?:

Do you have a resistor pellet in your ignition key?

Yes I do. However, this morning when I started the car to come to work the light came on (just like all the other ones do) and it went off (just like all the other ones do) and stayed off. I'm still curious what caused the light to come on in the first place, though...

The car lost contact with the resistor pellet in the key while you were driving, probably due to loose or dirty connections. It takes a full 60 seconds of loss-of-contact before the light will come on while driving, so maybe the key was slightly out of position or something.

If it can't get a good connection while you're trying to start the car, though, that will trigger the VATS, the starter won't crank at all, and you'll be in the penalty box with the Security light on solid for three minutes until the system resets. You might want to make sure the resistor contacts on your key are nice and clean, or use the other key if you have two, or get a new one, before the problem starts occurring more often. (You don't _have_ to go to the dealer for replacement resistor-pellet keys; Ace Hardware, among other places, has the necessary tester and key blanks.)