  We discuss domain wall solutions of 5-dimensional supergravity corresponding
to a cosine-superpotential, which is derived by a gauging of the two Abelian
isometries of the scalar coset SU(2,1)/U(2). We argue that this potential can
be obtained from M-theory compactification in the presence of G-fluxes and an
M5-brane instanton gas. If we decouple the volume scalar of the internal space,
the superpotential allows for two extrema, which are either ultra-violet or
infra-red attractive. Asymptotically we approach therefore either the boundary
or the Killing horizon of an anti-deSitter space or flat spacetime for a
vanishing cosmological constant. If the volume scalar does not decouple, we
obtain a run-away potential corresponding to dilatonic domain walls, which
always run towards a vanishing cosmological constant.
