Windows boss Steven Sinofsky has left Microsoft after 23 years of service, just days after he oversaw the launch of Windows 8 and Surface.
Sinofsky's departure takes place with immediate effect. He is to be replaced as head of Windows by Julie Larson-Green, who previously commanded Windows' business side.
Microsoft has not given a reason for Sinofsky's departure, although its timing raises questions over a link to lacklustre early sales of Microsoft Surface - as well as the kicking given to Windows 8 by some in the industry.
Launch figures for Microsoft Surface have not been disclosed, although the usually-ebullient Microsoft boss Steve Bullmer yesterday muttered that the tablet had "started modestly".
"Sinofsky is known inside and outside the company as a guy who got things done and done his way... Those who disagreed left or were shown the door."
Microsoft commentator Mary Jo Foley
Microsoft commentator Mary Jo Foley has suggested that the undisclosed reasons behind Sinofsky's departure may also have been more longer-term and political in nature.
A recent Microsoft statement hinted at change of business strategy for the company next year, with "less of an emphasis on the performance of Microsoft's five individualised business groups" and instead "deeper cross-organisation collaboration" - something Sinofsky was not accustomed with, Foley writes.
"Sinofsky is known inside and outside the company as a guy who got things done and done his way. Rumours regularly reappeared about Sinofsky angling to take over more business units. And until recently, it seemed like Microsoft's own senior leadership team, as well as Ballmer himself, had capitulated, allowing Sinofsky to make whatever management decisions he deemed fit. Those who disagreed left or were shown the door."
This tallies with Ballmer's statement about Sinofsky's exit, where he mentions the newly-promoted Larson-Green as having a "proven ability to effectively collaborate and drive a cross company agenda."
"Over the past few months we have delivered the foundation for a new era for Microsoft," Ballmer wrote in a statement to employees obtained by Venture Beat. "From Office to Bing to Windows Phone and Windows Azure, to Xbox and of course Windows and Surface and everything in between, we've unleashed a huge wave of devices and services that people and businesses love.
"We are facing a time of great opportunity. What we have accomplished over the past few years is nothing short of amazing, and I know we have more amazing in us. I am excited about our people, I am energized by our ability to change and grow, and I look forward to the success which lies ahead."