The EU's Executive Commission, which has been investigating Microsoft for four years, said recently collected information from businesses across Europe and the United States confirmed that abuses were "still ongoing."
"We have now a very strong case. The case as it stands now is too strong to ignore for the company at issue," said Commission spokesman Tilman Lueder. Wednesday's information did not include new allegations but substantiated existing complaints and Lueder said Microsoft could still face fines.
The Commission specifically charges Microsoft with unfairly leveraging the "overwhelmingly dominant position" Windows has in personal computers into the market for servers, which tie those desktop computers together.
It also alleges that Microsoft's inclusion of Windows Media Player in the Windows operating system hurts competing audiovisual software such as Apple QuickTime and Real Networks.
"In light of this evidence, the Commission's preliminary conclusion is that Microsoft's abuses are still ongoing," it said in a statement.
EU Competition Commissioner Mario Monti said the charge sheet sent to Microsoft also identifies "appropriate remedies," including additional code Microsoft would have to disclose to competitors in the low-end server market to ensure interoperability.
It also would have to either offer a version of Windows without the Media Player, or agree to carry rival players with Windows.
"This statement of objections ... gives Microsoft a last opportunity to comment before the commission concludes the case," Monti said. "We are determined to ensure that the final outcome of this case is to the benefit of innovation and consumers alike."
Microsoft has argued its 2002 settlement with U.S. authorities, combined with additional steps it has taken voluntarily, answer the challenge in Europe regarding media and server software.
There was no immediate comment from Microsoft's European headquarters in Paris.
In mid-March, the European Commission said its antitrust regulators wrestled with legal and political implications of cracking down on the U.S. software giant and that a final ruling was still "months" away.
The EU accuses Microsoft of violating antitrust laws by tying its Media Player into its Windows operating system, and by illegally withholding key data on Windows from rivals to try to win more of the market for low-end servers.
The Commission contacted music and movie companies as well as software developers earlier this year, asking them how they view the technologies they use to disseminate audiovisual material over the Internet.
"The replies highlighted that the ubiquity of Windows Media Player on PCs artificially skews their development incentives in favor of Microsoft," the commission said.
It said it got a similar response from businesses around Europe when it asked whether "interoperability considerations" between servers and PCs were a factor in their purchasing choices.