Greece debt crisis has nothing to do with banks. Google "cause of Greek debt crisis" and you will see. Banks are such small players in the overall Greek economy I bet you probably can't even think of the names of more than one or two Greek banks, if any at all.
Europe is in trouble because for decades, it has been giving its people a level of social welfare and support which Europe's economic growth cannot justify. Unemployment benefits, heavily subsidiaed healthcare and education, lifelong pension schemes etc. The debt has accumulated over decades and the system has reached crumbling point.