  M(atrix) theory is known to be mass-deformed in the pp-wave background and
still retains all 16 dynamical supersymmetries. We consider generalization of
such deformations on super Yang-Mills quantum mechanics (SYQM) with less
supersymmetry. In particular this includes N=8 U(N) SYQM with a single adjoint
and any number of fundamental hypermultiplets, which is a pp-wave deformation
of DLCQ matrix theory of fivebranes. With k >= 1 fivebranes, we show that a
rich vacuum structure exists, with many continuous family of solutions that
preserve all dynamical supersymmetries. The vacuum moduli space contains copies
of CP^{k-1} of various sizes.
