Adios, I was not responding directly to a statement made by Utah at the time, but instead to the question put forth by the original poster. I was trying to point out an assumption made by a free market (this may or may not be a free market assumption, I really don't know) and then point out that it is wrong.
As providing a specific example, I refer you to this link.
Games With Dominant Strategy Equilibrium
I figured that since John Nash basically revolutionized the way economists thought about economics, simply citing the example in the movie would be enough. Because I have no practical skill in economics, I cannot come up with a specific example involving market actors etc. The mathematical truth of the principle stated by Nash is evident to me, and being as such, it should be valid for many situations.