My yellow lights blink off and on when the car is turned off. Interesting as well, I have to lock the door now manually instead of using the key fob. It will unlock with the key fob, but not lock.
From your description (as light as it is), the symptoms lead me to believe you either have an open hatch somewhere, or one of the switches which detects open hatches is malfunctioning. In this instance, an open hatch could be the hood, trunk, or doors. The behavior you are describing with the lights flashing and the fob only working to unlock is what leads me to believe this. Most cars have a failsafe which won't allow the doors to lock via fob if one of the hatches are not completely secure (or it views it as such with a bad switch). You may or may not have an indicator on your dash showing up.