  Witten long ago pointed out that the simplest Kaluza-Klein theory, without
supersymmetry, is subject to a catastrophic instability. There are a variety of
string theories which are potentially subject to these instabilities. Here we
explore a number of questions: how generic are these instabilities? what
happens when a potential is generated on the moduli space? in the presence of
supersymmetry breaking, is there still a distinction between supersymmetric and
non-supersymmetric states?
