  We extend the four-dimensional gauged supergravity analysis of type IIB vacua
on $K3\times T^2/Z_2$ to the case where also D3 and D7 moduli, belonging to N=2
vector multiplets, are turned on. In this case, the overall special geometry
does not correspond to a symmetric space, unless D3 or D7 moduli are switched
off. In the presence of non--vanishing fluxes, we discuss supersymmetric
critical points which correspond to Minkowski vacua, finding agreement with
previous analysis. Finally, we point out that care is needed in the choice of
the symplectic holomorphic sections of special geometry which enter the
computation of the scalar potential.
