Disco 1 Won't stay locked

I had this a couple of weeks ago but seem to sort its self out now it's back.if I lock with the fob it locks then unlocks a second later, the alarm still arms as soon as I open a door the alarm and immobilizer kicks in.use the key to lock everything locks and stays that way.i do have a bad lock actuator/lock spring on the rear passenger door would this be the cause?

The drivers door actuator requires a slight adjustment, so after u have gained access, slacken the four screws of the actuators mounting plate and move the plate very slightly forward or backwards while operating the fob until the locking-unlocking functions fully, then tighten the four screws. Simples.

Ok thanks for that it's sorted it's self out again but will fix it at the weekend.