Newsted left Metallica on January 17, 2001, as plans were being made to enter the recording studio. He said he left the band for "private and personal reasons, and the physical damage I have done to myself over the years while playing the music that I love". During a "Playboy" interview with Metallica, Newsted said he wanted to release an album with his side project, Echobrain. Hetfield was opposed to the idea and said, "When someone does a side project, it takes away from the strength of Metallica", and that a side project is "like cheating on your wife in a way". Newsted said Hetfield had recorded vocals for a song used in the film "", and appeared on two Corrosion of Conformity albums. Hetfield replied, "My name isn't on those records. And I'm not out trying to sell them", and raised questions such as, "Where would it end? Does he start touring with it? Does he sell shirts? Is it his band?"