  We study the spin-1 chain with nearest neighbor couplings that are
rotationally invariant, but include both Heisenberg and biquadratic exchange,
with random strengths. We demonstrate, using perturbative renormalization group
methods as well as exact diagonalization of clusters, that the system generates
ferromagnetic couplings under certain circumstances even when all the bare
couplings are antiferromagnetic. This disorder induced instability leads to
formation of large magnetic moments at low temperatures, and is a purely
quantum mechanical effect that does not have a classical counterpart. The
physical origin of this instability, as well as its consequences, are
discussed.
