In Asia, it was seen as a banking crisis, in Europe it's now seen as a sovereign debt crisis, but in fact the crises nearly always originate in foreign trade and balance of payments imbalances.
Therefore, we need to explore the causality in more detail, from the current account deficits financed by hot money capital inflows, made possible by over-extended foreign banks and over-leveraged local borroweres. When these flows reverse suddenly, it causes a local financial contraction.
From where we sit in Lisbon, we have to wonder whether such "free capital flows" are such a good thing after all. In fact, they prove to be anything but "free".
See: Hot money