Sorry about bumping up an old thread.
I want to also confirm that I was able to fix this strange locking issue by removing the front-driver door trim (interior door panel) and spraying generous amount of lubricant on the door latch, door handle and door locking mechanism.
I think what was happening is that the power door lock linkages starts to bind (especially in cold weather), and the door lock actuator would incorrectly detect that the locking-knob is getting pushed down, when really it is just binding, as the actuator tries to push it up.
I didn't have to replace the actuator, but I did take it out in an attempt to diassemble the actuator internals and lube the internals. I couldn't figure out how to open the actuator back plastic cover, so I just cleaned it, and reinstalled.
Hope this helps someone else with the same problem. It was bothering me quite a bit.