  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 space 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 stable. The indeterminacy of the Frobenius map at this point
can be resolved by introducing Higgs bundles.
