Late last year, government lawyers overseeing Microsoft's antitrust compliance told the judge in the case that they had received a complaint about Windows Vista, but they didn't disclose who had made it. In this March filing, they updated the court on where the complaint stood:

At the last status conference, Plaintiffs reported that they had just received a middleware-related complaint. Since then, Plaintiffs have been investigating this complaint, including obtaining significant additional information from Microsoft and the complainant. Plaintiffs have not yet completed their investigation, but expect to do so by the time of the next Joint Status Report.

Again, there was no word of who had lodged the complaint. But as it turns out, it was Google, according to this New York Times story, published on the paper's Web site today. The issue: The built-in desktop search tool in Windows Vista, which Google says is causing problems for users of the Google Desktop Search program. From the New York Times story:

Google complained to federal and state prosecutors that consumers who try to use its search tool for computer hard drives on Vista were frustrated because Vista has a competing desktop search program that cannot be turned off. When the Google and Vista search programs are run simultaneously on a computer, their indexing programs slow the operating system considerably, Google contended. As a result, Google said that Vista violated Microsoft's 2002 antitrust settlement, which prohibits Microsoft from designing operating systems that limit the choices of consumers.

Google has asked the court overseeing the antitrust decree to order Microsoft to redesign Vista to enable users to turn off its built-in desktop search program so that competing programs could function better, officials said.

The U.S. Justice Department decided not to pursue Google's complaint, but some states are preparing to take action, according to the New York Times story.

A Microsoft spokesman, Jack Evans, said via phone this afternoon that Microsoft is working with state and federal officials to resolve the issue, but he added that Microsoft specifically designed the Windows Vista desktop search tool to avoid these kinds of issues by scaling back its indexing when other programs are running. Prior to Windows Vista's release, state and federal antitrust officials closely reviewed the new operating system, including the desktop search tool, and didn't raise concerns about the feature, he said.

See this story for more background and details.