Bank One Corp. said it had some bookkeeping problems in 1999 as it integrated the computer systems of the capital markets operations of the two banks that merged to form Bank One, the nation's fourth-largest bank holding company. However, the bank declined to comment on a report in the Wall Street Journal that said the problems have prompted an investigation by the regulatory arm of the National Assn. of Securities Dealers into potential violations that could result in fines of more than $1 million. The computer systems problems occurred when Bank One tried to integrate Banc One Capital Markets Inc. and First Chicago Capital Markets Inc. after the 1998 merger. A spokesman for NASD could not be reached Friday, a U.S. market holiday. Bank One shares closed Thursday at $31.44, up 69 cents, on the New York Stock Exchange.