Border Collie adopted, behavior problem

Question
I am a recent widow. Husband and I took in a border collie that a family had in an apartment. They had never had a dog of any kind, and he was alone until they all came home from work and school. We took the dog for company for me when I would be alone - both being dog lovers..we raised
English Springers at one time. I have a large farm house and lots of my own yard adjoined by fields of farm crops. First of all the dog has what I call overabundant joy - leaping and bounding and making a clacking noise as he sails by which scares some people. Actually he is a timid dog, not a violent one. But when he receives my abundant love he goes berserk - running around the house wildly. Outside off the leash which he is good on, he runs like the wind and is something to see! He doesn't bring back anything I throw but wants me to chase him. He is scared to death of my son who has a beard. He leaps and nips when I have been away. I have expressed grief sometimes and he comes to me, puts his paws in my lap and kisses me until I laugh - brings me all his toys. He cuddles next to me at night and sometimes sleeps with his head in my arms. He is very smart, and loving and I love him very much but don't know how to curb his wild behavior and nipping or clacking his teeth as he sails wildly by. I will not part with him. The vets say he is vicious but most of my friends find him loving and happy to see them. What shall I do? Also he sometimes disappears and reappears in nearby fields where he just sits and looks at me and ignores my calling him to come home. He is getting better about that when I have used a welcoming attitude when he has come and never punished him..or caged him up in the cage they left for him.

Answer
O my goodness.aw i think that your dog does these things because he loves the attention he never got be for and is afraid to lose you . also saying he is scared by your son,maby a guy from before owned the dog and abused it.its possible that your dog is scared of him because he looks like a past abuser he may of had!its very admiring that your dog looks up to you and it was a great act of kindness to take him in!and share your love with him hope all goes well