  We study a two-dimensional model for interacting colloidal particles which
displays spontaneous clustering. Within this model we investigate the
competition between the pinning to a periodic corrugation potential, and a
sideways constant pulling force which would promote a sliding state. For a few
sample particle densities and amplitudes of the periodic corrugation potential
we investigate the depinning from the statically pinned to the dynamically
sliding regime. This sliding state exhibits the competition between a dynamics
where entire clusters are pulled from a minimum to the next and a dynamics
where single colloids or smaller groups leave a cluster and move across the
corrugation energy barrier to join the next cluster downstream in the force
direction. Both kinds of sliding states can occur either coherently across the
entire sample, or asynchronously: the two regimes result in different average
mobilities. Finite temperature tends to destroy separate sliding regimes,
generating a smoother dependence of the mobility on the driving force.
