How can I sort out central locking prob on Micra 1.0 2003 please?

Central locking is making a loud noise which comes from the passenger door when the locking button is activated on the key fob. Also more disturbing is the boot keeps opening when driving along, what is going on and how can it be fixed? It's un-nerving and I would really appreciate some advice. HELP please!! PS Mine is a 3 door model micra