I think Ben is afraid that Locke may supplant him as leader. That was why he gave him the task to kill his father (knowing that being a murderer would somehow compromise Locke's affinity with the island).

As for the man who gave Locke the folder, I think a lot of the Others don't like Ben's leadership...or, at least, a small faction doesn't. The guy said that some of them thought that Ben should forget the fertility issue and concentrate more on the original, core goals which brought them to the island. (I can't remember the exact wording).

I think Ben kept Locke close to him (until he could walk again) and then, like Locke's dad after he got Locke's kidney, he didn't need Locke anymore and probably views him as a potential threat to his leadership. That little lecture on gamesmanship in The Man From Tallehassee (where he told Locke that his leadership has always been a little shakey) could figure into this, as well--showing the group that Locke doesn't have what it takes should push-come-to-shove. Sort of: "See? He can't be ruthless, and meet out justice like I can."

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charlie98210
"Whoa!" she said. "Cry 'Havoc!' And let loose the dogs of war!"
And, like Banquo's ghost, they just won't go away.