(BRUSSELS) - Microsoft's nine-year legal battle with EU antitrust regulators faces a crucial test on Monday when Europe's second-highest court rules in the company's appeal against a 2004 decision by the European Commission.

The following is a timeline of the main chapters in the saga between the US software giant and Europe's top competition regulator.

- December 1998: The US software group Sun Microsystems files a complaint against Microsoft with the European Commission. Sun alleges that Microsoft is elbowing it out of the market by refusing access to information to develop programmes for servers that could communicate with Microsoft products.

- February 2000: The European Commission opens a probe to determine if Microsoft is abusing its dominant market position in the launch of its Windows 2000 operating system.

- August 2000: Brussels issues a first charge-sheet against Microsoft based on Sun's complaints. It is followed by a longer list in August 2001 with elements targeting Microsoft's practice of bundling its Media Player programme with Windows and again in August 2003 when a new list is issued, proposing corrective measures.

- March 2004: The European Commission rules that Microsoft has not divulged information needed by rivals to develop programmes that work with Windows and is unsatisfied with the group on Media Player as well. EU regulators fine the company a record 497 million euros and demand corrective measures.

- June 2004: Microsoft files an appeal with the European Court of Justice in hope the ruling will be overturned. Within the month, Microsoft files a second appeal asking for the corrective measures to be suspended until there is a ruling on the first appeal.

- July 2004: Microsoft pays the fine.

- December 2004: The EU court deals Microsoft a setback, ruling that the company has to apply corrective measures even before there is a finding on the appeal against the Commission's decision.

- June 2005: Microsoft puts versions of Windows on the market stripped of Media Player.

- October 2005: The European Commission names an independent computer expert, Briton Neil Barret, to check that the corrective measures are carried out properly.

- December 2005: Based on conclusions from Barret, the Commission issues a new charge-sheet against Microsoft and threatens fines of two million euros per day.

- January 2006: Microsoft says it will release parts of Windows underlying source code.

- April 24-28, 2006: In a week-long hearing at the European Court of First Instance, Microsoft seeks to convince judges at Europe's second-highest tribunal that the European Commission's March 2004 decision is not justified.

- July 12, 2006: The Commission finds that Microsoft failed to fully respect its 2004 decision and orders the company to pay an additional fine of 280 million euros.

- October 2, 2006: Microsoft lodges an appeal against the new fines.

- March 1, 2007: The Commission finds that Microsoft is not licencing information to rivals at reasonable prices and threatens new fines.

- April 23, 2007: Microsoft answers the Commission's latest concerns and EU regulators have since then been examining whether the response is satisfactory.

- September 17, 2007: The European Court of First Instance is due at 9:00 am (0700 GMT) to hand down its ruling in Microsoft's challenge against the Commission's 2004 antitrust decision.

Microsoft or the Commission will then have up to two months and 10 days to lodge an appeal against the CFI's judgement to the European Court of Justice, Europe's highest tribunal.

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