The news, which came as remedies for Microsoft's software monopoly were being finalised, will scotch hopes of many IT directors that the action would lead to an early break-up of the company.
According to US reports, Microsoft is threatening to block proposals to process the case rapidly through the courts, unless the USgovernment agrees to narrow its restrictions on Microsoft's business practices.
The move, combined with Microsoft's threats to take the case to appeal, could delay the procedures for months or years.
Three times as many UK computer managers want to see Microsoft broken up as want to see it left alone, according to research by Computer Weekly and Harvey Nash. IT directors also favour forcing Microsoft to make Windows open source.