  After fixing a non-degenerate bilinear form on a vector space V we define an
involution of the manifold of flags F in V by taking a flag to its orthogonal
complement. When V is of dimension 3 we check that the Crepant Resolution
Conjecture of J. Bryan and T. Graber holds: the genus zero (orbifold)
Gromov-Witten potential function of [F / Z_2] agrees (up to unstable terms)
with the genus zero Gromov-Witten potential function of a crepant resolution Y
of the quotient scheme F / Z_2, after setting a quantum parameter to -1, making
a linear change of variables, and analytically continuing coefficients. The
crepant resolution Y (a hypersurface in the Hilbert scheme Hilb^2 P^2) is the
projectivization of a novel rank 2 vector bundle over P^2.
