central locking?

i have a renault clio mk 2 52 plate and the central locking works but it locks and unlocks locks and unlocks when the car is moving or if it hasnt been locked with the key, do u know what this might be? i have seen in the haynes manual that it might be something called the multi timer unit and if it is that it would cost £450 to get fixed so wanted to see what else it could be before i spend silly money. thanks

CRAIG W
October 2008