Broken Door Lock Question

Has anyone else had this problem? With the colder weather here, I've had the driver's door intermittently not open at all- from the inside or the outside, although the little knob/lock moves whenever I used the power locks.
All the other doors work fine.
I tried some WD40 in the mechanism of the door latch, but I don't know if it actually did any good. What seemed to work today was using the key and unlocking the door manually instead of by remote.
Also, I don't know if this is related, but I used to be able to unlock the trunk with the remote, and then unlock the rest of the car. Now, whenever I unlock the trunk first using the remote, the car will lock.
Anyone else had these problems? thanx,