  The Minimal Supersymmetric Standard Model has several flat directions, which
can naturally be excited during inflation. If they have a slow (perturbative)
decay, they may affect the thermalization of the inflaton decay products. In
the present paper, we consider the system of udd and QLd flat directions, which
breaks the U(1)xSU(2)xSU(3) symmetry completely. In the unitary gauge and
assuming a general soft breaking mass configuration, we show that for a range
of parameters, the background condensate of flat directions can undergo a fast
non-perturbative decay, due to non-adiabatic evolution of the eigenstates. We
find that both the background evolution and part of the decay can be described
accurately by previously studied gauged toy models of flat direction decay.
