driver door unlocking

2011 Malibu 4 cyl 6 spd auto: From time to time when I'm driving, the driver door unlocks. The other three remain locked. What could be going on?

Bad wire or electrical latch switch(also known as door ajar switch).......Tech II scan tool, would point this out easily...

I see, and thanks for the reply! Quite a versatile but pricey too, not one I would buy. Do you know, can this tool diagnose the problem even if the locks on all four doors work correctly? Or does the problem have to be "active" in order to diagnose?