Blame the Fed. (pdf) From the conclusion:
In this paper I have provided empirical evidence that government actions and interventions caused, prolonged, and worsened the financial crisis. They caused it by deviating from historical precedents and principles for setting interest rates, which had worked well for 20 years. They prolonged it by misdiagnosing the problems in the bank credit markets and thereby responding inappropriately by focusing on liquidity rather than risk. They made it worse by providing support for certain financial institutions and their creditors but not others in an ad hoc way without a clear and understandable framework. While other factors were certainly at play, these government actions should be first on the list of answers to the question of what went wrong.