But "far more often than not, the software performed as designed and the failure was due to the software, in fact, being counterfeit and the customer simply not wanting to believe it," he wrote.

While installing and running the WGA is technically optional to Windows users, users complained about the way it was automatically installed as a "critical" update. Those who declined to install WGA were reminded about WGA every time they rebooted their PCs.

Microsoft abandoned those features in late June. But users must still install and pass WGA in order to be eligible to download certain free software, such as the company's upcoming Internet Explorer 7.0 Web browser and its antispyware program, Windows Defender.

The company also faces two class-action lawsuits related to WGA.