Stocks got off to a weak start Friday as the dollar strengthened and bonds and commodity prices moved generally lower. The Dow Jones industrial average and S&P 500 slumped 0.6%, and the Nasdaq fell 0.5%. Volume was down about 6% on the Nasdaq and NYSE exchanges. Economic news was reasonably positive on the stock market today. Producer prices rose more than forecast in May, suggesting some pricing power at the producer level.