Microsoft announced last week that it would not appeal a December ruling by the European Court of First Instance that sanctions imposed on the software company for a breach of antitrust laws should be implemented immediately.
Microsoft had been hoping to delay implementation until it had completed its appeal against the original antitrust ruling, but instead the software giant has to comply with the sanctions within six weeks of the December ruling.
That deadline expires this week.
This means that Microsoft now has to disclose details of the interfaces required for third party products to be able to "talk" with Windows, to any business wishing to develop and distribute work group server operating systems.
Microsoft also has to offer for sale in Europe a version of Windows without Windows Media Player, although it can also market the operating system with Windows Media Player.
Speaking to Reuters, Commission spokesman Jonathan Todd confirmed that the remedies should be implemented within a matter of weeks rather than months, and that in the event of a delay, the Commission had the power "to decide to impose penalty payments up to five percent of Microsoft's average daily turnover."
Reuters notes that, based on last year's turnover, this could amount to around $5 million a day.
The Commission has also squashed Microsoft's plans to name its new versions of Windows the "Windows XP Home Reduced Media Edition" and the "Windows XP Professional Reduced Media Edition".
According to reports, the Commission felt that the title was likely to discourage purchasers from buying the Media-Player-free software.
"While we believe that name is fully compliant [with the antitrust ruling], in the spirit of compromise we have agreed to make a change in the name of the product," Microsoft spokesperson Jim Desler told PC World.
Microsoft and the Commission are in talks ahead of the deadline to resolve any outstanding issues.
Speaking to Reuters, a Microsoft spokesman confirmed, "Microsoft is committed to complying with the Commission's decision and is working with the Commission toward that goal."