The big credit ratings agencies -- S&P, Moody's -- faced enormous criticism in the United States for their role in the housing crisis. In Europe, many countries now say those same firms are feeding the debt crisis. So European regulators are pushing back.

Over the weekend, it was announced that George Papandreou would step down as Greek prime minister. Italy, and its leader Silvio Berlusconi, could be next.

Without a tidy solution to the eurozone debt crisis, Greece may have to leave the eurozone. Could it really happen?

Taking a closer look at why Greek Prime Minister George Papandreou asked for a referendum on a eurozone deal made last week.