Superman is faster than a speeding bullet and more powerful than a locomotive. But a piece of kryptonite smaller than your cellphone can leave him so weak that he gets sand kicked in his face. Supercomputers, too, have their kryptonite: Machines capable of doing trillions of operations per second and storing trillions of bytes of data have been turned into gargantuan paperweights. But their vulnerabilities come in several forms that will have a bigger effect as chips shrink and the machines become more complicated.
