Heavy metal band Metallica discovered a demo of their song "I Disappear" had been circulating across the network before it was released. This led to it being played on several radio stations across the United States and alerted Metallica to the fact that their entire back catalogue of studio material was also available. On March 13, 2000, they filed a lawsuit against Napster. A month later, rapper and producer Dr. Dre, who shared a litigator and legal firm with Metallica, filed a similar lawsuit after Napster refused his written request to remove his works from its service. Separately, Metallica and Dr. Dre later delivered to Napster thousands of usernames of people who they believed were pirating their songs. In March 2001, Napster settled both suits, after being shut down by the Ninth Circuit Court of Appeals in a separate lawsuit from several major record labels (see below). In 2000, Madonna's single "Music" was leaked out onto the web and Napster prior to its commercial release, causing widespread media coverage. Verified Napster use peaked with 26.4 million users worldwide in February 2001.