  We study the effects of rotation on the torsional modes of oscillating
relativistic stars with a solid crust. Earlier works in Newtonian theory
provided estimates of the rotational corrections for the torsional modes and
suggested that they should become CFS unstable, even for quite low rotation
rates. In this work, we study the effect of rotation in the context of general
relativity using elasticity theory and in the slow-rotation approximation. We
find that the Newtonian picture does not change considerably. The inclusion of
relativistic effects leads only to quantitative corrections. The degeneracy of
modes for different values of $m$ is removed, and modes with $\ell=m$ are
shifted towards zero frequencies and become secularly unstable at stellar
rotational frequencies $\sim$ 20-30 Hz.
