2 yr aggressive male biting problem

Question
I have a 2 yr old neutered male that has been professionally trained.  He has snapped at people in the past and has been socialized since he was 6 weeks old.  I am the alpha and he is perfect with my entire family.  He knows all of his commands and listens 99% of the time.  

The problem is yesterday he bit someone after playing with them for 2 hrs.  He had given this person paw, other paw, his ball and played fetch, etc.  The dog was laying on the floor next to us and my friend went to pet the dog and he bit him in the hand requiring a ER trip.

I feel this is something innate with the dog, and something that he just cant control.  I cant continue to risk him attacking someone and have it become more severe that what has already happened.  

Any advice would be greatly appreciated.

Answer
I can't disagree with you.Although there are other options. One thing I would so is that  I would have him vet checked to begin with. Sometimes physical problems can cause erratic behavior in dogs. You can find these problems with any breed. I would also check his food, make sure he isn't on a food that is too high protein.High protein dog foods are for dogs who are actively productively working every day. Working dogs need a job. Try to give him one. Get him involved in routine obedience work. Take him for walks twice per day every day. with a pack so that he is actually doing something. Make sure at least a couple of times a week he has HEAVY physical exercise. Until his tongue hangs out. Walking him is essential. These highly intelligent animals are not couch potatoes. They are working dogs who need a job. I can't emphasize this enough. Try adding new tricks to his bag of tricks. several times a month to give him something to occupy his mind.