The recent drop in PC sales is a big challenge for Microsoft. New quarterly profits dropped slightly to $6.62 billion. The results would have been much worse if not for strong demand for business software and services, and a solid holiday season for the Xbox game console. Sales of Windows and Office products could suffer as growth shifts away from the personal computer industry toward  tablets and other mobile devices. Other earnings results this week have been mixed. Financial stocks rose with stronger than expected reports by Bank of America and Morgan Stanley. IBM earnings beat expectations, but Google's fourth quarter results came in worse than expected.

Megaupload.com, among the world's biggest file-sharing sites, has been shut down by the federal government. The U.S. accuses the site of facilitating millions of illegal downloads of films, music and other content - costing the industry half-a-billion dollars in lost revenue. The founder and three employees are in custody.

International debt inspectors have arrived in Greece to see if the government is doing enough to qualify for bail out money. A default by Greece could have wide implications for the European economy. The inspectors are from two European authorities and the International Monetary Fund. Greece is now negotiation with private creditors - trying to reduce the cost of its debts

Funding for startups rose 19 percent in the fourth quarter as venture capitalists funneled money into more companies in the Internet, clean technology and other sectors. According to new research from Thomson Reuters, startup investments grew to $6.57 billion in the October-December quarter from $5.52 billion in the same period in 2010.