Microsoft Corp. on Thursday reported quarterly double-digit profit growth for a period that saw the software giant bid farewell to Bill Gates as it girded for a costly battle in the Internet market against Google Inc. However, Microsoft also saw its shares tumble more than 6% in late trading, to $25.75, in after-hours trading as its forecast for the current period came up shy of Wall Street's expectations. In the regular session, the stock closed up 26 cents at $27.52. For the company's fiscal fourth quarter, which ended June 30, Microsoft earned $4.3 billion, or 46 cents a share, up from $3 billion, or 31 cents a share, for the corresponding period a year ago. Total revenue rose 18% to $15.84 billion.