How to change an agressive dog into a loving friendly dog.

My dog is fine around me my husband and our children,but it doesnt matter who comes to our house or where we take her she gets very mean.She has bitten a child already in the 7 months we have had her.She gets very aggressive towards others,almost like she want to eat them..lol..How can I make her stop?? I think she is afraid others are trying to hurt or or something.I do know she is very protective of us,but because of this our children cannot have their friends over anymore and its hard for us to invite friends into our own home.Is there a solution to this problem???

What will cause her to lick non stop.She licks constantly and it drives me crazy.She has to lick the face,legs,hands,any body part that she is near:~) Is that normal??

[lindapalm]

I would suggest getting some Cesar Millan tapes, I watch him on National Geographic channel, and he handles cases like this all the time, and he always gets good results.