  Recently a new type of Kramers-Fokker-Planck Equation has been proposed [R.
Friedrich et al. Phys. Rev. Lett. {\bf 96}, 230601 (2006)] describing anomalous
diffusion in external potentials. In the present paper the explicit cases of a
harmonic potential and a velocity-dependend damping are incorporated. Exact
relations for moments for these cases are presented and the asymptotic
behaviour for long times is discussed. Interestingly the bounding potential and
the additional damping by itself lead to a subdiffussive behaviour, while
acting together the particle becomes localized for long times.
