Regardless of what caused the crisis, the fact is that the crisis is happening and these bubble bursts appear to get worse over business cycles. This seems to point to a need for at least some basic regulation of our financial markets - regardless of what was or wasn't regulated in the past.
No doubt that the general "laissez-Faire" resurgence of the 1980-? fostered an enviornment of more and more risk-taking from all sides. Deregulation DID happen - even if we assume (incorrectly) that it just happened in the goods and services market - all markets are interconnected. As one industry gets lax it demands more debt, putting more and more pressure on the financial sector to do deals it should not.
It makes no difference to me whether Republicans or Democrats or both de-regulated in the past. Let's focus on a solution instead of pointing blame (yes, that means you too Speaker Pelosi!)