Key dates in Microsoft Corp.'s (MSFT) relationship with European Union antitrust regulators:

— 1994: EU and U.S. Justice Department settle allegations about Microsoft's software licensing and marketing behavior. Microsoft agrees to stop making computer makers pay a fee for every PC sold, regardless of whether it contained Microsoft software.

— 1997: EU forces Microsoft to release Santa Cruz Operation Inc. from contract that requires it to include Microsoft code in its variant of the Unix operating system and pay royalties whether it used code or not.

— March 1998: EU makes Microsoft alter licensing agreements with Internet service providers that allegedly violate competition rules.

— May 1998: U.S. Justice Department and 20 states sue Microsoft, charging it thwarted competition to extend monopoly.

— October 1998: Justice Department sues Microsoft, alleging it violated 1994 consent decree by forcing computer makers to sell its Internet browser along with Windows.

— December 1998: EU begins investigating complaint from Sun Microsystems Inc. (SUNW)  that Microsoft withheld software code rivals needed for its server software to interface as well as Microsoft's own.

— February 2000: EU begins investigating complaints that Windows 2000 would give Microsoft dominant position in e-commerce.

— April 2000: U.S. District Judge Thomas Penfield Jackson (search) finds Microsoft violated U.S. antitrust law and attempted to monopolize the Web browser market.

— June 2000: Jackson orders Microsoft split into two companies.

— August 2000: EU sends formal charge sheet accusing Microsoft of abusing its Windows monopoly to dominate the market for server software.

— April 2001: EU closes investigation into Microsoft's investments in European digital cable TV. Company agrees to modify agreements.

— June 2001: U.S. appeals court throws out Jackson's breakup order.

— August 2001: EU sends new charge sheet to Microsoft stemming from Windows 2000 case, accusing it of violating antitrust law by tying its media player into Windows. It also merges case with charges regarding server market.

— October 2001: Microsoft, Justice Department tentatively agree to settle U.S. antitrust case.

— March 2002: Microsoft proposes concessions to EU that it says go beyond those agreed to in the United States to help rivals' equipment operate with Windows.

— November 2002: U.S. District Judge Colleen Kollar-Kotelly (search) approves most provisions of Microsoft's settlement with the U.S. government. It prohibits Microsoft from retaliating against PC makers; lets customers remove icons for Microsoft features and requires that Microsoft disclose more technical data to software developers.

— January 2003: Computer, phone and Internet companies file EU complaint charging Windows XP is designed to extend Microsoft's dominance into new markets such as instant messaging and mobile phones.

— August 2003: Backed by new evidence it says show ongoing abuses, EU sends third charge sheet to Microsoft and gives it "last chance" to defend itself before demanding changes in Windows.

— January 2004: European Union antitrust chief Mario Monti (search) prepares draft ruling against Microsoft.

— February: Monti rejects Microsoft offer to include rival digital media software on CD-ROMs sold with Windows.

— March 15: Advisory committee of EU national regulators unanimously backs Monti's draft decision.

— March 16: Microsoft CEO Steve Ballmer (search) holds face-to-face talks with Monti.

— March 18: EU says talks failed.

— Wednesday: EU levies record fine of 497 million euros ($613 million). Orders Microsoft to offer Windows version without digital media player and to release programming code to makers of rival server software.