According to Kinetic Molecular Theory, molecules have no kinetic energy at .
See
If the molecules have no kinetic energy, they have no translational motion.
However, according to quantum mechanics, all particles have a zero-point energy, even at absolute zero.
The requires some motion even at absolute zero.
If there were no motion, we would know simultaneously the position and the momentum of the particle. The Heisenberg Uncertainty Principle forbids this.
Thus, there is some motion even at absolute zero.
At , liquid helium does not freeze at any temperature because of its zero-point energy.
Easy, to the point, nice picture on this website: http://chemistry.about.com/od/chemistryfaqs/f/absolutezero.htm
