Not sure how your locks work, but it could be a bad switch. On manually operated (that is to say, the switch directly drives the servo) electronic systems, you have to have a contact closure long enough to allow the servo to go full travel.
If your symptoms are as you say, there can't be anything wrong with the servo since you can unlock it from the passenger side.
So, what I think is happening is that the drivers side switch is making poor contact and not driving the system properly, bouncing open and closed at the same time, or something like that.
The other possibility is a bad controller if you have one, or a wiring problem.
It's hard to say you have to replace the actuator or mechaism with the problem as you describe it. A problem with the drivers lock mechanism itself would render it non-operational from either door.
EDIT: Reading your post again: it's not the LOCK that is the problem? It's only when you use the interior door handle to open the door when it's locked? Please clarify, I'm sorry but I'm a bit confused. (Nothing new there...)