Investor blowback at Chesapeake Energy (CHK) over management scandals unseated four board members. And some shareholders sent a rare signal of no-confidence to leadership at retailing giant Wal-Mart Stores (WMT) over bribery investigations in Mexico. Chesapeake Energy, the nation's No. 2 natural gas producer, has been wracked by low prices for that fuel, and by news that CEO Aubrey McClendon borrowed as much as $1.1 billion against his stake in