Microsoft has hit back at European Commission accusations that it has not complied with demands to provide data relating to an anti-competition case.
Microsoft's dominant position has brought it focus from regulators
It was given until Wednesday to prove it had provided rivals with computer codes that would let them develop products to work with Windows systems.
Microsoft said that Brussels ignored a 75-page report from the company explaining and addressing the concerns.
The company is facing daily fines of 2m euros (£1.4m; $2.4m).
"The Commission has ignored critical evidence in its haste to attack the company's compliance," Microsoft said in a nine-paragraph statement.
"Microsoft has complied fully with the technical documentation requirements," it added.
It went on to accuse the Commission of helping create the problems.
"The Commission repeatedly refused to clearly define its requirements and concerns, despite repeated requests and accommodations by Microsoft," it said.
Microsoft's problems date back to March 2004, when Brussels hit it with a record 497m euro fine for abusing its dominant position.
As well as the fine, Microsoft was ordered to share technical data that would allow rivals to make their programs compatible with Microsoft's products.
The Commission complained in December that the company was dragging its feet and not living up to its requirements.
Microsoft complained on Wednesday that that was not the case
"Hundreds of Microsoft employees and contractors have worked for more than 30,000 hours to create over 12,000 pages of detailed technical documents," it said.
Microsoft has called for an oral hearing, that must be held before any fines can be imposed.