The European Commission appointed a British computer scientist Wednesday to oversee whether Microsoft Corp. is complying with a 2004 antitrust decision.
The EU executive's naming of Neil Barrett as trustee to monitor the U.S. software giant's compliance comes amid further informal complaints about Microsoft, which could lead to the opening of a new case.
"The monitoring trustee's role is to provide impartial expert advice to the Commission on compliance issues," said the Commission in a statement.
EU regulators ruled last year that Microsoft had abused its near-monopoly in desktop computer systems to illegally dominate the media software market and threaten the position of competitors selling office networking software.
The Commission fined Microsoft €497 million and ordered it to share code with rivals and offer an unbundled version of Windows without the Media Player software.
Microsoft is appealing the ruling, but in the meantime has produced a Windows version without its Media Player.
A question remains over Microsoft's promise to give rival software-makers some cost-free, additional access to its software protocols - the complex and closely guarded procedures that allow software programs to interact with operating platforms such as Windows.
The Commission chose Barrett out of a shortlist of candidates put forward by Microsoft itself, the AP reports.