AN FRANCISCO (Reuters) - Apple Inc Chief Executive Tim

AN FRANCISCO (Reuters) - Apple Inc Chief Executive Tim Cookon Monday  replaced the heads of its software and retail units in the company's  most sweeping executive shake-up in a decade following embarrassing  problems with its new mapping program and unpopular store-related  decisions. Software chief Scott Forstall, who oversaw the launch of the flawed  mapping software and much criticized Siri voice-enabled assistant, will  leave Apple next year and serve as an advisor to Cook in the meantime. Forstall, seen as a polarizing figure inside Apple, had been billed as  one of the future candidates to take the top job at Apple. He was the  executive behind the panned Apple Maps app that the company announced  with much fanfare in summer. The moves, which come a little more than a year into Cook's tenure as  CEO, were described by Apple as a way to increase "collaboration" across its hardware, software and services business. "These changes show that Tim Cook is stamping his authority on the  business," Ben Wood, analyst with CCS Insight, said. "Perhaps  disappointed with the Maps issues, Forstall became the scapegoat." Critics of the maps debacle, which led Cook to apologize to customers,  had been calling for Forstall's head. "Does Apple have a Scott Forstall  problem?" Fortune editor Philip Elmer Dewitt wrote on Sept 29.