central locking sometimes stops me getting into drivers side?

every now and again using remote key doesn't open drivers door but all others.release button pops open as if door is open but remains locked.pressing open and lock on key has to be pressed fairly hard and more than once to open and lock I have changed battery in key but still happening.this happened when i drove off and the central locking system locked and I couldn't open any doors with central locking buttons in the car.Only happened once though.