Nikkei briefly down 4 percent as autos fall

TOKYO (Reuters) - Japan's Nikkei stock average fell 4 percent on Monday after a U.S. autos task force rejected restructuring plans submitted by General Motors and Chrysler LLC, sending automakers tumbling. In a stunning reversal for management at both automakers and GM investors and creditors who had bet on a softer line, the Obama administration task force warned both firms could be put through bankruptcy to slash debts