The company is notifying customers about the tactic after inquiries from The Associated Press. Microsoft says it has no plans to sell the data collected by Media Player, which comes free with the Windows XP operating system. The company said last month it had sold more than 17 million copies of Windows XP.
"If you're watching DVDs you don't want your wife to know about, you might not want to give her your password," said David Caulton, Microsoft's lead program manager for Windows Media.
Downloading CD information such as the disc name and track list, is a common practice used by almost every computer CD player. But downloading DVD information is new, and has the potential to be sensitive especially in the case of racy or violent movies.
Microsoft's original privacy statement informed customers that they were downloading the information about CDs but never stated that the information was being stored in a log file on each computer.
The new statement makes clear that information is being downloaded for both DVDs and CDs, but does not explain how users can eliminate or get into the log file.
"It definitely could have been clearer and more specific about DVDs," Caulton said.
Clearing the list of songs and movie titles would cripple Media Player. Stopping the program from collecting any more information would mean changing the software's settings, but that would disable Internet broadcasts.
As part of downloading the information about songs and movies from the Web site, the program also transmits an identifier number unique to each user on the computer. That creates the possibility that user habits could be tracked and sold.
Privacy experts said they feared the log file could be used by investigators, divorce lawyers, snooping family members, marketing companies or others interested in learning about a person's entertainment habits.
Microsoft said the program creates the log file so a user does not have to download the same information over again. The company said the ID number was created simply to allow Media Players users to have a personal account on the Web site dealing with the software, and is not used in the chapter information download process.
Neither is sold or shared with others, and no information is collected on Microsoft's servers that would be personally identifiable, officials said.
Jonathan Usher, another Windows Media executive, said Microsoft has no plans to market aggregate information about its customers' viewing habits, but would not rule it out.
"If users tell us that they want the ability to get recommendations, that's something we could look into on the behalf of users," Usher said.
In a recent memo, Microsoft cairman Bill Gates ordered his company to check for privacy and security concerns before adding new features.
"Users should be in control of how their data is used," Gates wrote. "Policies for information use should be clear to the user. Users should be in control of when and if they receive information to make best use of their time."
Privacy activists said the feature does not meet Gates' standard.
"For users to have real control, they should have a basic understand of what's happening behind the scenes, then have control over individual documents and files," said Ari Schwartz of the Center for Democracy and Technology.
"This is a tool that could have been built with privacy in mind," Schwartz said.
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