November 1998:The EU's antitrust agency looks into a complaint from Sun Microsystems that claims Microsoft had failed to provide information needed by the Solaris operating system to interoperate with PCs running Windows.

August 2000: European Commission formally charges that Microsoft withheld technical information from rivals so it could dominate the server software market.

August 2001: Commission levels second charge at Microsoft -- that it violates antitrust laws by tying its Windows Media Player with the OS in an attempt to freeze out RealNetworks' RealPlayer -- and merges it with the server accusation of the year before.

January 2003: EU receives complaints from Microsoft competitors that Windows XP is designed to extend Microsoft's desktop monopoly into instant messaging and mobile phones.

August 2003: EU gives Microsoft "one last opportunity to comment" before it wraps up its antitrust probe.

March 18, 2004: Direct negotiations between Microsoft's chief executive Steve Ballmer and EU Commissioner Mario Monti break down.

March 24, 2004: EU fines Microsoft 497 euros ($613 million), and orders the developer to release a version of Windows XP without Media Player. Also demands Microsoft release protocols to rival server software makers.

June 2004:Microsoft appeals Commission fine and orders with the European Unions Court of First Instance.

December 2004: Court of First Instance rejects Microsoft's request for a suspension of the Commission's orders while the case is on appeal. Microsoft begins the process of licensing communication protocols to rivals.

June 2005: Microsoft announces Windows XP Home Edition N and Windows XP Professional Edition N -- both sans Windows Media Player -- to meet 2004 order's demands.

December 2005: European Commission accuses Microsoft of dragging its feet in providing protocol documentation to other server software makers, files formal objection and threatens 2 million euro per day ($2.37 million at the time) fine. Penalty will be backdated to December 15, 2005.

January 25, 2006: In an attempt to placate the Commission, Microsoft announces it will license source code for Windows Server to rivals. Company's general counsel, Brad Smith, says "The Windows source code is the ultimate documentation."

March 30-31, 2006: Microsoft appears in closed hearing before European Commission, argues it is meeting the antitrust agency's documentation requirements.

April 24-28, 2006: Court of First Instance holds week-long appeal. Microsoft argues that "companies need to have confidence they won't be forced to hand over their valuable intellectual property to their competitors[and] companies need to have confidence they can develop new products with the features their customers want."

July 3, 2006: EU member states' antitrust regulators vote unanimously to back the 2 million euro ($2.54 million) daily fine.

July 12, 2006: Commission slaps Microsoft with 280.5 million euro ($358 million) fine for non-compliance, and threatens 3 million euro ($3.8 million) per day fine after July 31 if the company continues to thumb its nose at the EU.