  We investigate the stability of massless topological black holes in AdS_d
when minimally coupled to a scalar field of negative mass-squared. In many
cases such black holes are unstable even though the field is above the BF bound
and the geometry is locally AdS. The instability depends on the choice of
boundary conditions for the scalars: scalars with non-standard (Neumann)
boundary conditions tend to be more unstable, though scalars with standard
(Dirichlet) boundary conditions can be unstable as well. This leads to an
apparent mismatch between boundary and bulk results in the Vasiliev/Vector-like
matter duality.
