It's never different. The cause is not in the free market. The cause is the lack of a free market.
Ron Paul understands the issues perfectly. He writes:
The reality is that the Federal Reserve relentlessly expanded the money supply through artificially low interest rates for over two decades, and this expansion of easy money caused a wholly predictable bubble. To a myopic Keynesian regulator, the bubble may appear to be caused by greed, but in truth it is completely predictable that humans will act in their own perceived self interest. If the Fed wants to dole out artificially cheap money, people and businesses- including Wall Street businesses- will line up to take it. We can condemn this as greed, but the fundamental problem is Fed policy itself. There will always be demand for cheap money, but we should not allow the Fed to debase our currency and create bubbles of false prosperity to satisfy that demand.