Gwen Stefani, lead singer with California's No Doubt, has always seemed like one of those pop stars who's perfectly satisfied to forego credibility in search of ever greater record sales and the celebrity that goes with them. There comes a time, however, when even the prettiest girl gets tired of being called a bimbo by the sneering music critics and sets out to prove them wrong. Last year's collaborations with Moby and Eve were a useful start, but the real onslaught comes with Rock Steady, her band's fifth and easily most ambitious album. The No Doubt template of new wave pop and ska punk has been overhauled in favour of electrically-charged rock singalongs, infectious white reggae and graceful, ice-cool mood pieces. Celebrity friends such as The Neptunes, William Orbit and Prince, meanwhile, have been drafted in to give the production that necessary oomph. It all amounts to an unexpectedly entertaining pop album, packed with potential hit singles, and a career re-invention that could make even Madonna feel jealous.