The March roll-up update for Windows 10 appears to be causing headaches for users, some of whom have been left with computers that don't boot up after the patch has been applied.
Microsoft issued the update on March 2 Australian time and users who installed it via Windows Update soon after started complaining of problems.
Some experienced extremely long start-up times, with their devices taking over an hour to reach the user account login prompt.
Others said they were forced to boot from USB thumb drives with an earlier installation version of Windows 10 and attempt startup repair.
Also reported were computer slow-downs, the My Documents folder and Start Menu disappearing, and "blue screen of death" crashes.
Installing the update itself has been problematic for Windows 10 users, with error codes 0x80070003, 0x80070020, 0x8070bc9 and others displayed.
As a temporary workaround, some users said uninstalling the KB3140743 update returned their systems to a stable state. However, Windows 10 will attempt to install the update again.
The comprehensive KB3140743 update contains cumulative bug fixes and enhancements released previously for users who might have otherwise missed them.
The update takes Windows 10 to OS build 10586.122.
Microsoft also released the preview build 14729 of Windows 10 under its Insider early adopter program.
Build 14729 contains improvements to Microsoft's Edge web browser and the Cortana personal digital assistant that stop them from crashing for users who have roaming profiles. The new build also fixes other problems, such as device drivers from Windows Update causing blue screen of death on certain computers.
Windows 10 engineering systems team boss Gabe Aul has noted that build 14279 had multiple issues, including system freezes for Microsoft's Surface Pro 3, Pro 4 and Book devices, requiring users to hold down the power button to force their devices to do a hard reboot.