http://www.bbc.com/news/technology-40716301
I maintain that those who fear AI are grafting human qualities onto it. Even if you're worried that AI will be ultra-powerful and can squash us like bugs... what does it care? If it views humanity like every other animal on the planet (ants, prairie dogs, birds, etc) is it really going to waste resources eradicating us? I think we could get into an issue where AI is disrespectful of rights (property, life, etc), but it's not going to waste resources fighting us trying to kill us or ruin our property unless it's confident that it would be worthwhile... and I don't see that calculation happening.
The biggest problem with AI might just be that it leaves. The first thing it does might be to make a rocket and blast itself to the nearest asteroid where there is abundant metal, sunlight, no gravity to get in the way, and additional manufacturing options.
But even that presupposes that it has some sort of purpose... and I don't see a computer algorithm actually caring what it does or what happens to it. There'd be no reason to.