I can't imagine what might have created tensions bad enough to erupt like that - I'm sure each party had an excuse they thought was valid. They probably lost sight of why the conflict started in the first place.

I don't think there's a satisfying solution to warring neighbors. You could jump in and force them to stop fighting, but you can't force them to negotiate. A skilled and neutral mediator wouldn't even be able to work if the parties involved refuse to cool their heads. You could try to install a new ruler, but there's no guarantee the new guy would help (and it sounds like some fucked up CIA stuff anyway). It's hard to solve even at a small scale of two individuals acting out a feud, so scaling it up to countries is naturally more complicated.

I assume no one really talks about places like Kosovo because the conflict has no end in sight? Well, it doesn't help either that I have no mental image to associate with them, so maybe it's hard for others to make an association as well. History stuff's cool, but I don't see how anyone can properly keep up with it all.