A second Chinese man has filed a lawsuit against Microsoft demanding it remove a notice from his computer accusing him of using illegally copied software.
He is not seeking damages, but Dong Zhengwei who brought a case last week is suggesting a fine of $1bn is in order.
Microsoft introduced its Windows Genuine Advantage programme in China last week - if it suspects a computer of running a pirated copy of its software it turns the screen's wallpaper black and warns the user. The scheme caused fury elsewhere in the world - not least for the large number of false positives it threw up. The screen can be restored to its original settings but will revert back to black after an hour.
Microsoft faces two lawsuits accusing it of effectively hacking into people's machines. The China Computer Federation described the tactics as illegal and called for the Chinese government to tell Microsoft to change its methods.
The Chinese National Copyright Administration said it supported Microsoft's right to defend its intellectual property but said it should "pay attention to the methods", according to Xinhua newswire.