11/13/2012 07:05 pm ET

Why Sinofsky Left Microsoft? 5 Theories On The Windows Head's Departure

Steven Sinofsky, head of Windows operating system, has packed up the knick-knacks he had accumulated on his desk over the nearly 25 years he had worked at Microsoft and left its offices for the last time.

The departure of such a big-time exec, announced late Monday, is big news, considering it happened just weeks after the release of Windows 8,

Unfortunately, the company hasn't exactly been transparent about the decisions (mutual or otherwise) that led to the move. Sure, Microsoft's CEO Steve Ballmer wrote that "Sinofsky has decided to leave the company," but didn't say much more. So what was the real reason Sinofsky left?

That was the question tech reporters had Tuesday. Some dusted off Rolodexes and called up sources at Microsoft to figure it out. Others just openly speculated. In either case, here are five theories put forward to explain Sinofsky's departure:

5 Theories On Why Sinofsky Left Microsoft