So when Mustaine was diagnosed with radial neuropathy (strained nerves in his left arm and hand) in 2002 and broke up the band, there were no tears or gnashing of teeth. For two years, Mustaine rehabbed his arm, and has returned with The System Has Failed, featuring guitarist Chris Poland (whom he fired after the band's seminal 1986 release Peace Sells . . . But Who's Buying?). While still featuring some of the more radio-ready midtempo material of the '90s, the balance resurrects Megadeth's thrashier roots, making this the band's most ferocious sound in a dozen years. Welcome back!