Autumn goes bonkers when she hears a car pull up the driveway, and she and Gizmo bark until the people are in the house. Then once she has sniffed them and we have told her that they are ok, Autumn will go lay down (well most of the time she does! LOL) A lot of the time she wants center of attention and tries to get extra pats from the visitors.
Gizmo freaks everytime we have company. She growls and barks if it is someone she doesn't really know. She gets scared and nervous with people she doesn't know. Never have I had them turn aggressive and bite though so I am not sure how to help or offer help with your problem.