Microsoft is pushing hard to get its next-generation Windows operating system ready for a public launch in January, but now it has a new hurdle: the European Commission has raised concerns about Vista. The Redmond company said a delay may occur if the EU demands changes to the product.

Microsoft has had a tumultuous relationship with the European Union after being found guilty of violating antitrust laws in March 2004. The Commission long accused the company of not complying with the ruling, while Microsoft has responded by publicly chiding regulators for ignoring key information.

But pressure from the Commission has not stopped with Windows XP. Back in March, the EU expressed concern regarding Vista's built-in Internet search functions and new document features. It warned that if it finds evidence of anti-competitive behavior, a new case against the Redmond company could be made.

Microsoft responded to the Commission and is awaiting a response, it said in a statement Thursday. "Once we receive the Commission's response, we will know whether the Commission is seeking additional product design changes that would result in delay in Europe."

"Generally Microsoft is targeting world-wide availability of Windows Vista for corporate customers in November and retail availability in January, with the exact delivery date to be determined by results from the final testing that is now underway," a company spokesperson said.

Meanwhile, the European Parliament is beginning to question the Commission's pursuit of Microsoft. A letter sent to Antitrust Commissioner Neelie Kroes by four MPs warned that Microsoft delaying or pulling products from the European market would only hurt the EU. However, Parliament has little jurisdiction over the antitrust Commission.