Agressive after dinner

Question
I have a beagle-shepherd mix, 14 months old.  I have had him for 4 weeks now.  He is a loving, friendly dog.  But every night, right about sundown, he will start chewing his bones and start running laps around the house and growling.  During this time, if someone walks past him he will snap and not listen to commands.  After 15 minutes of this, he lays down and falls asleep.  About an hour later I then wake him, put him in his pen for the night.  At all other times during the day he is obedient and loving.  What causes this daily agression, and how do I deal with it?

Answer
I am at a loss to explain just why he is doing that.  I do have an answer, strong leadership on your part.  The key to most behavior problems is approaching things using the dog's natural instincts.  Dogs see all the people and dogs in the household as a pack with each having their own rank in the pack and a top dog.  Life is much easier if the 2 legged pack members outrank the 4 legged ones.  You can learn to play the role of top dog by reading some books or going to a good obedience class. A good obedience class or book is about you being top dog, not about rewarding standard commands with a treat. Start at http://www.dogsbestfriend.com/  For more on being top dog, see http://www.dogbreedinfo.com./topdogrules.htm