Image credit: ABC News

Less than a month after Microsoft launched its Windows 8 operating system, Steven Sinofsky, the president of Microsoft's Windows division, is departing after 23 years with the company.

"It is impossible to count the blessings I have received over my years at Microsoft," Sinofsky said in a statement this evening. "I am humbled by the professionalism and generosity of everyone I have had the good fortune to work with at this awesome company."

Microsoft CEO Steve Ballmer returned the gratitude in his own statement.

"I am grateful for the many years of work that Steven has contributed to the company," Ballmer said.

From Windows 8 to Outlook.com to Windows Phone 8, Sinofsky has been credited with a lot of the recent change at Microsoft. In 2009, he joined the Windows team after the Vista operating system debuted and headed up the development of Windows 7 and then Windows 8, which marks the biggest change to Windows since Windows 95.

"We started to look back and we said, 'Wow, the user interface, the experience, the form factors, the kinds of PCs were all developed in the mid 1990s,'" Sinofsky said last month in an exclusive interview with ABC News at Microsoft's campus in Redmond, Wash. "We looked and we said, 'Things are so different. We need to envision a new kind of software for those scenarios, because the world is a different place.'"

Many even anticipated that Sinofsky would be the next CEO of the company. Microsoft did not explain why Sinofsky was leaving so soon after the Windows 8 launch, but, according to technology website All Things D, Sinofsky "was viewed at the top levels as not the kind of team player that the company was looking for."

The technology site compared the exit to the recent exit of Apple's Scott Forstall.

Julie Larson-Green will step in for Sinofsky and lead the Windows software and hardware teams. She was responsible for Windows 8 interface and experience.

"Her unique product and innovation perspective and proven ability to effectively collaborate and drive a cross company agenda will serve us well as she takes on this new leadership role. All of the current Windows engineering teams will report into Julie, and Julie will report to me," Microsoft CEO Steve Ballmer wrote in a company-wide email.

Ballmer highlighted Larson-Green's ability to work with other teams, which is becoming increasingly important as Microsoft continues to integrate its services, including Xbox, Windows, Windows Phone and more.

ABC News interviewed both Larson-Green and Sinofsky last month. The video clip is below.