Strange, indeed. I've used D'Addario strings almost exclusively for many years on several guitars, and I can't remember what you describe ever having happened to me. Sure, I occasionally break strings--and almost always on bends--but it is the string itself that breaks, most often at the bridge, less often at the tuner peg, and only rarely somewhere in between. The major differences are that I run 10's at the high E, not 9's, and I buy them in 10-pack sets, not individual strings (although I do use individual strings if I break a B or high E early in the life of a set). I wonder if the greater flexibility of the lighter string makes them more prone to this unraveling issue you're seeing?