  Let X be a projective curve of genus 2 over an algebraically closed field of
characteristic 2. The Frobenius map on X induces a rational map on the moduli
scheme of rank-2 bundles. We show that up to isomorphism, there is only one (up
to tensoring by an order two line bundle) semi-stable vector bundle of rank 2
(with determinant equal to a theta characteristic) whose Frobenius pull-back is
not semi-stable. The indeterminacy of the Frobenius map at this point can be
resolved by introducing Higgs bundles.
