What's it mean when your speakers start to buzz?

I have this nice little Bose system hooked up in my office. Two small speakers and a sub-woofer. It's a multi-media system meant for computers. But I use it to hook up a portable CD player and my iPod. It takes up almost no space and makes for some pretty nice sounds. Until today...

The right speaker is occasionally letting out a nasty little buzz. I've checked all the cables and connections and everything looks okay.

I'm not big on equipment knowledge. I just know what sounds good. I don't know how nothing works. Is my speaker dying? Can I save it?