Source PC World: http://www.pcworld.com/article/2911792/keep-windows-10-preview-up-to-date-or-face-a-dead-pc.html Testers running Windows 10’s preview must keep the OS relatively up to date or face a bricked PC that won’t boot. The first three builds of Windows 10 Technical Preview—9841, 9860 and 9879, all released in 2014—will refuse to boot at the end of April, according to a message posted by a Microsoft support engineer on the company’s discussion forum. Personal computers running the three 2014 builds have been displaying warnings of the impending expiration for the last two weeks. Starting Wednesday, the PCs have been rebooting every three hours, another hint from Microsoft to update. “Approximately 2 weeks after the license expires, the build will no longer boot at all,” said a support engineer identified only as “RajithR” in a message dated April 10. That step is to start April 30. If you're on the treadmill you must keep moving or you might face plant.