The European Commission has refused to give Microsoft more time to respond to the latest antitrust charges from the Commission.
Microsoft will now have to submit its response to the EC's statement of objections by 15 February. The EC has accused the software giant of not providing adequate documentation to enable rivals to create server software that will work with hardware running on the Microsoft operating system.
Microsoft had previously submitted instructions for server interoperability but in December the EC described them as "incomplete and inaccurate" and requested "complete and accurate specifications".
The EC also turned down Microsoft's request to see some internal EC correspondence, between commissioners and others involved in the case, which the software giant said was pertinent to its rebuttal of the antitrust charges.
Microsoft's associate general counsel, Horacio Gutierrez, said that the EC had removed a "fundamental right" of the software giant's defence.
He said in a statement: "Last week the Commission said it was premature for Microsoft to allege they are riding roughshod over our rights of defence. Today we are less than a week away from the deadline for filing our response and have been denied access to the complete file, so I suppose it is now official and they are indeed riding roughshod over our defence rights."