  We address the important practical issue of understanding, predicting and
eventually controlling catastrophic endogenous changes in a collective. Such
large internal changes arise as macroscopic manifestations of the microscopic
dynamics, and their presence can be regarded as one of the defining features of
an evolving complex system. We consider the specific case of a multi-agent
system related to the El Farol bar model, and show explicitly how the
information concerning such large macroscopic changes becomes encoded in the
microscopic dynamics. Our findings suggest that these large endogenous changes
can be avoided either by pre-design of the collective machinery itself, or in
the post-design stage via continual monitoring and occasional `vaccinations'.
