Doors unlock while driving

This has happened twice.
The first time the doors unlocked as I was driving. I would manually lock the doors; and then a minute later they would unlock again. I tried leaving them alone; and I heard another unlocking attempt.
I took the car to the person who installed my Viper alarm system. The system checked out fine. He programmed out the Viper's unlock command; that would have activated when the keys were removed from the ignition.
For weeks after that I had no problem.
It happened again a few days ago.
The GM shop man said over the phone that maybe there was mointure in the locking mechanism.

I'm surprised that the GM shop man didn't blame it on the aftermarket alarm. That's usually the first thing they look for.

When you say locking mechanism, I think if the latches and lock rods. You know, the mechanical parts. It could be that the lock switches are corroded but unless you leave the windows open while it's raining, that wouldn't be a likely suspect.

Do you have any difficulty locking/unlocking by pressing the door switches? What model Viper alarm do you have?

I have no problem manually locking/unlocking the doors. The Viper model # is 560XV.

Wit the info provided, I'd put my money on the alarm. If it happens with any regularity (I.E. hitting bumps in the road or after a certain amount of time) I would probably start by temporarily disconnecting the alarm the lock/unlock wires from the alarm. The Vipers have these wires in a separate 2 or 3 pin harness, usually plugged into the side of the module, and are green and blue. Try this out for a day or two and see if it continues to happen.

Also, what year and trim level is your car? Do you have central locking (use the key in the door and all the doors lock/unlock)?

Wit the info provided, I'd put my money on the alarm. If it happens with any regularity (I.E. hitting bumps in the road or after a certain amount of time) I would probably start by temporarily disconnecting the alarm the lock/unlock wires from the alarm. The Vipers have these wires in a separate 2 or 3 pin harness, usually plugged into the side of the module, and are green and blue. Try this out for a day or two and see if it continues to happen.

Also, what year and trim level is your car? Do you have central locking (use the key in the door and all the doors lock/unlock)?

It is a 1997 Bonneville SE. It does not have central locking. The fact that it only happens once in a while: does that still possibly point to the Viper system?

Well, it's tough to blame it on any OEM problem so by deafult the alarm is suspect. On vehicles equipped with central locking, there is a wire (LT/GRN) that connects to the Remote Accessory Controler (RAC) to unlock the rest of the doors. This is a ground signal and the wire connects right to the door's key cylinder. There's not much keeping these connections from getting corroded and could potentially be shorted to ground causing the unlocking. But you don't have the wires...