  We present explicit numerical evidence of reflection-positivity violation for
the lattice Landau gluon propagator in three-dimensional pure SU(2) gauge
theory. We use data obtained at very large lattice volumes (V = 80^3, 140^3)
and for three different lattice couplings in the scaling region (beta = 4.2,
5.0, 6.0). In particular, we observe a clear oscillatory pattern in the
real-space propagator C(t). We also verify that the (real-space) data show good
scaling in the range t \in [0,3] fm and can be fitted using a Gribov-like form.
The violation of positivity is in contradiction with a stable-particle
interpretation of the associated field theory and may be viewed as a
manifestation of confinement.
