"How do you talk with a problem player" is right up there with "how do you ask your crush out" in the realm of "there is no one correct way to do this, but hundreds of good and bad ways depending on the people involved."
That said, there are some things you can do.
1.) Ask why the player is engaging in the problem behavior. It could be ignorance, it could be griefing. People engage in antisocial behavior for all sorts of reasons in their minds, and sometimes they don't even realize they are doing it.
2.) Approach the player in whatever method is best for both of you. Generally, talking to someone when alone is the best method. Sometimes, a cooler detached method is needed.
3.) Be honest. If the issue is ruining someone's fun, advise that there is an issue and that things will need to change in order to move forward.
4.) If all else fails, advise that perhaps finding a game that supports their type of play is best.
And here are some things you should avoid.
1.) Focusing your issues via the game. Punishing the player by breaking the rules, targeting the PC, or having the hand of God smite them. If you're not the DM, having PvP issues with the problem player is just as bad.
2.) Ganging up. You don't need the whole group there to talk with the problem player. That said, if multiple players have a problem, its not a bad thing to mention that others (NEVER NAMED WITHOUT PERMISSION) are also having issues.
3.) Letting things fester until things blow up.