NEW YORK, Oct 23 - Stocks fell at Thursday's open, extending Wednesday's rout, after weak results from companies like software maker Computer Associates International Inc. and a steep sell-off in Japan. The Dow Jones industrials <.DJI> fell 30 points, or 0.31 percent, to 9,567. The tech-packed Nasdaq Composite Index <.IXIC> dropped 19 points, or 1.03 percent, to 1,878. The broad Standard & Poor's 500 <.SPX> lost 3 points, or 0.35 percent, to 1,026. Both the Dow and the Nasdaq had their biggest daily percentage drops since Sept. 24.//