Original: The band underwent serious "band therapy," engaging in several long talks to work out the members' differences after accusations from Dirnt and Cool that Armstrong was "the band's Nazi" and a show-off bent on taking the limelight from the other band members.
Simplified: They took "band therapy," talking for a long time to work out the members' differences after accusations from Dirnt and Cool that Armstrong was "the band's Nazi" and a show-off bent on taking the limelight from the other band members.