With Kiedis often absent from recording due to his drug problems, Flea took a larger role in the writing process, and sang lead on his song, "Pea". "One Hot Minute" was released in September 1995 after several delays. It departed from the band's previous sound, with Navarro's guitar work incorporating heavy metal riffs and psychedelic rock. The band described the album as a darker, sadder record. Kiedis's lyrics addressed drugs, including the lead single, "Warped", and broken relationships and deaths of loved ones, including "Tearjerker," written about Kurt Cobain. Despite mixed reviews, the album sold eight million copies worldwide and produced the band's third number-one single, "My Friends". The band also contributed to soundtracks including "" and "Beavis and Butt-Head Do America." The band began the tour for "One Hot Minute" in Europe in 1995; the US tour was postponed after Smith broke his wrist. In 1997, several shows were cancelled following deteriorating band relations, injuries, and Navarro and Kiedis's drug use. They played their only show of the year at the first Fuji Rock Festival, in Japan. In April 1998, the band announced that Navarro had left due to creative differences; Kiedis stated that the decision was "mutual". Reports at the time, however, indicated that Navarro's departure came after he attended a band practice under the influence of drugs. With no guitarist, the Red Hot Chili Peppers were on the verge of breaking up. In the years following Frusciante's departure, it became public that he had developed a heroin addiction that left him in poverty and near death. Flea convinced Frusciante to admit himself to Las Encinas Drug Rehabilitation Center in January 1998. His addiction left him with permanent scarring on his arms, a restructured nose, and dental implants following an oral infection. In April 1998, Flea visited the recovered Frusciante and asked him to rejoin the band; Frusciante began sobbing and said nothing would make him happier. In June 1999, after more than a year of production, the Red Hot Chili Peppers released "Californication", their seventh studio album. It sold over 16 million copies, and remains their most successful album. "Californication" contained fewer rap songs than its predecessors, instead integrating textured and melodic guitar riffs, vocals and basslines. It produced three more number one modern rock hits, "Scar Tissue", "Otherside" and "Californication".