  We study the Quantum-Mechanics on the hyper-Kahler manifold that is the
blow-up of an $A_1$-singularity. This system is relevant for M(atrix)-theory as
it was conjectured to describe scattering in the "noncommutative" deformation
of a free 5+1D tensor multiplet in the sector with two units of longitudinal
light-like momentum.
