  In this paper we consider classical and quantum corrections to cosmological
solutions of 11D SUGRA coming from dynamics of membrane states. We first
consider the supermembrane spectrum following the approach of Russo and
Tseytlin for consistent quantization. We calculate the production rate of BPS
membrane bound states in a cosmological background and find that such effects
are generically suppressed by the Planck scale, as expected. However, for a
modified brane spectrum possessing enhanced symmetry, production can be finite
and significant. We stress that this effect could not be anticipated given only
a knowledge of the low-energy effective theory. Once on-shell, inclusion of
these states leads to an attractive force pulling the dilaton towards a fixed
point of S-duality, namely $g_s=1$. Although the SUGRA description breaks down
in this regime, inclusion of the enhanced states suggests that the center of
M-theory moduli space is a dynamical attractor. Morever, our results seem to
suggest that string dynamics does indeed favor a vacuum near fixed points of
duality.
