Microsoft just beat quarterly earnings estimates. So why is the stock falling?Microsoft (MSFT -5.19%) stock is slipping in Thursday's trading following the company's recent quarterly report. The tech giant's share price was down 5.4% as of 3 p.m. ET.After the market closed yesterday, Microsoft reported results for the fist quarter of its current fiscal year -- which ended Sept. 30. While sales and earnings for the period came in ahead of Wall Street's expectations, investors aren't satisfied with the compan ...