Microsoft has made some stumbles in the mobile world, but a strategy shift made more than a year ago will soon pay dividends, the company's top Windows Mobile executive said in an interview with CNET News. Andy Lees, the executive brought over from the server unit a year ago, said that Microsoft's efforts to make sure that its mobile software could run on a wide range of phones resulted in an operating system that failed to take advantage of advances in hardware. "We aimed to go for a lower common denominator," Lees said. Microsoft was also limited by the origins of Windows Mobile, which was developed to power handheld computers that neither connected to a network nor handled voice. "We started out when we were in PDAs (personal digital assistants) and then a phone got strapped to the back of the PDA," Lees said. The company also failed to recognize that phones--even those that were used for business--were still as much personal as they were professional