  We discuss a metal-insulator transition caused by random couplings of
magnetic moments in itinerant systems. An analytic solution for the single
particle Green function is derived from dynamical self consistency equations,
the corresponding density of states is characterized by the opening of a gap.
The scaling behavior of observables is analyzed in the framework of a scaling
theory and different crossover lines are identified. A fluctuation expansion
around the mean field solution accounts for both interaction and localization
effects in a consistent manner and is argued to be relevant for the description
of the recently discovered metal-insulator transition in 2d electronic systems.
