  We consider a simple quiver gauge theory with gauge group U(r1) x U(r2) and a
Higgs field in the bi-fundamental representation. The back-ground for this
theory is a compact K\"ahler manifold M. For a careful but natural choice of
Higgs field potential the second order field equations can be replaced with a
set of first order BPS equations. We show that the theory admits two energy
gaps: The vacuum is topologically trivial but has finite, non-zero energy and
is not a BPS state. The second gap lies between the vacuum and the first BPS
state. In this gap we find a ladder of states with non-trivial topology, at
equidistant energy levels. We give a semi-explicit construction for such
topologically non-trivial non-BPS states.
