Source code do Windows 2000.

“Microsoft is investigating how a file containing some protected source code to Windows 2000 was posted to several underground sites and chat rooms.

A spokesman said late Thursday that incomplete portions of Windows 2000 and Windows NT were illegally posted to the Internet.”

— ZDNet

“On Thursday, Microsoft became aware that portions of the Microsoft Windows 2000 and Windows NT 4.0 source code were illegally made available on the Internet. It’s illegal for third parties to post Microsoft source code, and we take such activity very seriously.”

— Microsoft