One of our chuchus has this weird behavior, he seldom barks, but will attack a stranger who will pick up something from our house...also he will run after a guest who will leave the house without anybody from our household seeing him/her at the door, he is untrained by the way, just developed this behavior all by himself.

Anybody here with silent type dogs?

That's not good. The seldom barking thing might just be related to his personality. Some dogs just don't bark. The attacking or running after guests thing has to do with his lack of training.

My dog rarly barks, she is afraid of everything and and will only bark at strangers she hasnt met before and things that are strange to her ( she barked at a stick poking out of water once) Try to introduce your dog to whoever you bring into your house and have them pet your dog a lot so your dog will know that those people are friendly.