Therese, Have you ever watched the Dog Whisperer? There are a few snippets on this website and more info about times when it comes on, etc.
http://channel.nationalgeographic.co...preview_1.html
This will not help your immediate problem, but it is an interesting show about dog behavior and how to achieve a calm, submissive state for a dog that is showing dominance.
I had a Chesapeak Bay Retriever that didn't like other dogs (or people for that matter) and would growl and even lunged after a few people. We never could get her to behave. I think if I had known about the techniques that Cesar Milano (Dog Whisperer) uses, she would have gotten along better with other dogs and people and been a happier dog.
The great thing about the show is that he says over and over that all dogs can be taught how to behave in the "pack" with correct techniques and repetitive reinforcement.
Good luck,