  We construct an MSSM-like model via Pati-Salam from intersecting D-branes in
Type IIA theory on the $\Z_2 \times \Z_2'$ orientifold where the D-branes wrap
rigid 3-cycles. Because the 3-cycles are rigid, there are no extra massless
fields in the adjoint representation, arising as open-string moduli. The
presence of these unobserved fields would create difficulties with asymptotic
freedom as well as the prediction of gauge unification. The model constructed
has four generations of MSSM matter plus right-handed neutrinos, as well as
additional vector-like representations. In addition, we find that all of the
required Yukawa couplings are allowed by global symmetries which arise from
U(1)'s which become massive via a generalized Green-Schwarz mechanism.
Furthermore, we find that the tree-level gauge couplings are unified at the
string scale.
