Will computers become self-aware one day? What happens then?

Oh man, I'm really interested about this kind of stuff. I don't think it's possible though. Robots need to be programmed to follow a certain set of rules in reaction to stimuli. Humans have the gift of being unpredictable. They are also able to use their ideas in a much more fluent and uncontrolled way. I think these will keep us from creating robots that can accurately represent human behavior.