It could be that your master switch or the driver switch has an intermittent
contact - mine did that after I left the window open while it rained (if you
don't like the weather in CT, you wait a minute - weather changes quickly
here).

If it happens frequently, see if you can disconnect the switch panel's
connector:  first try the passenger door switch, see if it goes away. If
not, try disconnecting the driver's side switch.
(it often pops out easily if you put a flat screwdriver under the side
towards the font of the car)

Remco

My 1997 Nissan Quest has starting -- intermittently -- locking the
doors on it's own.

I'll walk away from the unlocked van and come back later and sometimes
it will have locked itself up. Sometimes all doors, sometimes only a
couple.

I live in the remote woods, no one else around. I've never used the key
fob remote that came with the vehicle.

And the vehicle -- at least from what I can read in the owners manual
-- does not seem to have an "auto lock" function that can be programmed
into the factory installed alarm.

Any thoughts?