Microsoft must think beyond the PC if it is to weather the changes due to hit in the next five years.
The warning was given by Microsoft's chief software architect Ray Ozzie in a memo penned soon after he announced he was leaving the company.
In it, Mr Ozzie said that the last five years had been "breathtaking" and expected the next five to be the same.
But, he said, the strengths that had helped Microsoft grow in the past now risked holding it back.
The memo, called "Dawn of a New Day" mirrors one Mr Ozzie wrote soon after taking over from Bill Gates as the man in charge of charting the development direction of Microsoft's portfolio of programs.
BBC News - Ray Ozzie tells Microsoft to 'go beyond the PC'