  We study the creep motion of an elastic string in a two dimensional pinning
landscape by Langevin dynamics simulations. We find that the Velocity-Force
characteristics are well described by the creep formula predicted from
phenomenological scaling arguments. We analyze the creep exponent $\mu$, and
the roughness exponent $\zeta$. Two regimes are identified: when the
temperature is larger than the strength of the disorder we find $\mu \approx
1/4$ and $\zeta \approx 2/3$, in agreement with the
quasi-equilibrium-nucleation picture of creep motion; on the contrary, lowering
enough the temperature, the values of $\mu$ and $\zeta$ increase showing a
strong violation of the latter picture.
