The reason why humans can compete with computers is because humans think in a different way.
Every human immediately knows that this is position is a draw, despite having the worst bishop in history. Rybka rates it as +7 for white.
If you look at the word "Sfbawrzabrfoawiawsdhasghe" you immediately know that you have never seen it before*. A computer would have to check the whole database....which could take hours....to come to the same conclusion.
Computers are very good at adding 1+1, but that's about it.
* You even know that you will probably never see it again - crystal ball?