The EC (European Commission) has laid out specific antitrust concerns it has about Vista, Microsoft's long-anticipated OS (operating system), EC spokesman Jonathan Todd said today.
"We are concerned about the possibility that Vista will include software elements that are available separately either sold by Microsoft or by other software companies," Todd said.
"There is also the possibility that we won't have all the technical information needed for competitors to make their software interoperable with Vista."
The EC said it told Microsoft about these concerns in a letter sent last week to CEO Steve Ballmer.
Microsoft declined to comment on the letter, which it said it hasn't yet received.
The concerns echo the findings in the EC's 2004 antitrust ruling against Microsoft, which found Microsoft guilty of bundling its Media Player software into the Windows OS. It also ruled that the software giant had stunted competition by not allowing competitors the information needed to make their servers interoperate with PCs running Windows.
The concerns about Vista, which is due to go on sale to consumers at the beginning of next year, include plans to bundle an internet search function, a DRM (digital rights management) program and software for creating a fixed document format comparable to the PDF format, and security features, Todd said.
"We are concerned that computer manufacturers and consumers won't have a proper choice of software," he said.
Microsoft responded with a statement saying: "We have a responsibility to make our products better and more secure for our customers in a manner that respects all laws and competition standards.
"We are building Windows Vista to provide the most secure personal computing environment and to provide unprecedented opportunities for other companies throughout the industry."
The firm added that consumers are free to use a wide range of competing products, and that Windows Vista "is designed to respect the choices that consumers make".
Microsoft said it has included partners and competitors in its planning of Windows Vista, to allow them to build products and services that work with the OS.
Keeping the industry and regulators informed of its product development plans has been, and will remain, a priority, Microsoft said.
No formal investigation has been opened yet, but Todd said: "If our concerns are confirmed and we conclude that Vista violated European competition rules then we would open a new case."
Todd was responding to questions prompted by comments made by Competition Commissioner Neelie Kroes in an interview in The Wall Street Journal Europe today.
"We expect that Microsoft will design Vista in a way which is in line with European competition laws," Kroes said in the interview. "It would be rather stupid to design something that is not."
Kroes wrote a letter to Ballmer at the beginning of last week, detailing specific concerns about Vista.
"Microsoft asked us what could be problematic with Vista, so we told them," Todd said.
The warning about Vista comes a day before Microsoft's top lawyers gather with regulators and rivals at a Brussels hearing about the company's compliance with the 2004 ruling.
In December the EC issued a lawsuit against Microsoft, accusing it of failing to honour the 2004 ruling. Microsoft requested the hearing so that it could refute the accusation and explain to regulators that it is in compliance with the ruling.
If Microsoft fails to change the EC's mind it faces daily fines of up to €2m (about £1.37m) until it is deemed to be in compliance with the 2004 ruling.