Microsoft has one week left to bend to the will of the European Commission.
If Brussels is not satisfied by then, it says daily fines will begin.
Those could go as high as nearly five million euros.
Last year the software giant paid an almost half-billion-euro fine after it was ruled to have abused its dominant market position.
But other requirements have yet to be fulfilled.
Selling to computer makers a version of its Windows operating system without Media Player audio-visual software.
That way, the computer makers could offer Windows with rival audio-visual programs.
And: Microsoft is also supposed to furnish them with inter-product operational codes at reasonable prices.
Thirteen months after a European legal ruling in the matter, the company still has not complied to the satisfaction of the Commission.