I just Had ED-E go hostile and ruin the boomer quest. I went back to an earlier save but he does it every time. I can move forward by dropping him at the save point but am wondering if this is a bug or if some followers are just unacceptable to some factions.

ED-E's a little crazy. I'm not sure if it's an intended effect or an actual code glitch, but sometimes he just goes crazy. I suggest reloading the immediate save before he starts a fight, take him as far from people as possible in the area, and tell him to wait for you. I've had it happen in Primm, Camp McCarran, and inside the Atomic Wrangler.

My Ed-E in my current game goes hostile on the people in Vicky and Vance's. This is the quirkiest follower I've ever had.