Thanks. I'm always thinking in give a little chat or e-mail about "normal human behavior" before campaign, but with my lack of time (due to university) I usually don't do it. Now I know it's necessarily
My big rules are no evil characters, and no lone wolf characters, but really it boils down to "don't be an ass". I also try to push people towards reasonable backstory (or emphasize that some of their backstory might not actually be as they understand it) and positive motivations in addition to "revenge on X".
I had this conversation just a few days ago with a new player; his character had his forest cut down and hated loggers. As a backstory it's OK, but it doesn't do anything to explain why the character was exploring dungeons a long ways from his homeland, or what happens after he kills a bunch of loggers. It was what I see as "negative" motivation. In conversation we decided that while the destruction and revenge could be a factor, a stronger motivator was the desire for a new forest of his own. Essentially we leapt from "kill loggers" to the classic D&D endgame "ruling a realm", which is a lot more interesting and has a lot more plot hooks to take advantage of.
Edit: Don't be afraid to question the players about what's going on. Call a 5-minute break, take the player into the other room, and run through the character's actions. If they're intent on being a lone wolf, ask them why they're in the party at all. And take a stand. The PLAYER needs to make a character that can interact with and contribute to the party. That's pretty basic. No one player has precedence over the rest. Remember that the goal is to understand the player/character's decisions, and not spoil them, though. There are almost always more players then there are DMs, and they will come up with ways to surprise you. Let it happen. Last session my players "overcame" a hobgoblin band by giving them the particular chest they demanded - but they switched the contents and gave the wrong key. It was a REALLY obvious ploy, but I hadn't thought of it and the hobgoblins didn't have instructions to check the box...so they took their rag-filled box and left. (They'll be back, and they'll be pissed, but I about died laughing at how simple it was.)
I did have to have a conversation with a player about his evil lone wolf character a month or two ago. He understood the problem, and while he is still making bizarre characters, they're much less disruptive to the party (a cleanliness-obsessed wild mage bridge troll with a flea circus is the current one...and there might be something about a portable bridge. And a goat & cart. It's all a bit confusing, really.) Your player sounded like a problem beyond the character, however, and that's not cool.