The reasons for the housing crisis are investigated in this collaborative effort with "Fortune" magazine, which features "Fortune" managing editor Andy Serwer, CNN's Gerri Willis, New York Times columnist Paul Krugman, securities expert Janet Tavakoli, investment strategist Peter Dunay and Lenox Financial CEO Jon Shibley. Included: insights from former Federal Reserve chairman Alan Greenspan and former Treasury Secretary Larry Summers.

• Anderson Cooper