Car won't lock or unlock
 

Recently, I noticed that I had to unlock the car twice with the key for it to open. Now when I press the lock or unlock button (on the key or inside the car) the drivers looks makes the effort to lock/unlock but it won't work. I have to use the key to manually lock or unlock the drivers door.

Does anybody know what might be happening, or has anybody experienced the same thing?

Any help will be appreciated.

Lock/unlock
 

This happened with mine a couple years ago. Bought a new battery for the remote key and that fixed it. Might be this is your problem - hope so as its an easy fix!

I might try that, but the rest of the doors work with the remote. And the same thing happens when I use the lock/unlock button inside the car.

I had that happen in my old Acura twice, turns out was was the lock motor

Today I took my C300 to a workshop. The technician had it scanned and he says the computer suggests it is the door lock module of the drivers door. Any suggestions, or anyone has heard of this?

Sounds right

If your other doors unlock fine but your drivers door does not, and the drivers door is making a effort to unlock (IE actuator noise = connection is good) then you need a new door lock actuator.

Item 13 in the picture below.
http://www.genuinemercedesparts.com/.../5/5777328.gif