  We develop the theory for stick-slip motion in ultra-thin liquid films
confined between two moving atomically-flat surfaces. Our model is based on
hydrodynamic equation for the flow coupled to the dynamic order parameter field
describing the ``shear melting and freezing'' of the confined fluid. This model
successfully accounts for observed phenomenology of friction in ultra-thin
films, including periodic and chaotic sequences of slips, transitions from
stick-slip motion to steady sliding.
