WGA has a checkered history, and has often from Windows users. In June 2006 it pushed a version of WGA to XP users via Windows Update by tagging it as a "high priority" update that was automatically downloaded and installed to most machines. That event is the one at the center of the current lawsuit.

A year later, a riled thousands of users who were mistakenly fingered for running counterfeit copies of Windows.

The lawsuit, which seeks class-action status, has not yet been scheduled for trial.

In related news this week, in a separate case involving its "Windows " marketing program, Microsoft asked U.S. District Court Judge Marsha Pechman to to use the Windows Update service to distribute a class member notification to nearly 150 million Windows users.