I found out the drivers door latch wasn't working properly the other week when I opened the 'locked' door before my wife unlocked the doors. The alarm went off but we could not lock the door from the remote, inside button or manually. It made sounds like the mechanism was working but just didn't work. After searching the web, sounds like this is a common problem with 05 to 07 models especially. Bought a new latch from Rocklin LR and tackled it last night.
Not a technically difficult but a pain in the rear eating to the cable releases. There are good instructions on the web so I won't go over the whole job but I was able to do t without removed the window regulator completely. Be careful not to torque the cable to the inside door latch like I did when removing the latch mechanism.
Check your doors because it could have been broken for months without us knowing.