Microsoft released March Patch Tuesday a few days back, and now users are reporting issues with update described as KB3033929 on Windows 7 and Windows Server 2008 R2, which was released to enhance the support for SHA-2 code signing in Windows.
Apparently after the update is installed the operating system cannot validate the fix and causes infinite reboot loop PCs and servers, according to the Microsoft Support forums:
“I’m having problems with the KB3033929 update from the latest run of Tuesday patches. After installation the PC reboots, but during the boot up configuration of the patch it fails and Windows starts reverting the configuration and reboots. And then it starts all over again a couple of times until it eventually boot into Windows.”
As a possible temporary fix, one of the users in the forum recommended setting Windows as the default boot loader in the BIOS as the GRUB boot loader seems to be getting in the way.
This is an issue affecting a small number of computers and Microsoft has yet to comment on a permanent fix. If you still haven’t installed the update, it would be wise to go to Windows Update, right-click the update KB3033929, and click “Hide this update” option.
Also, try to uninstall the update (if you can). Go to Windows Update in Control Panel, then click View update history, click the Installed Updates link, look for KB3033929, select and right-click it, and choose Uninstall.
Source Microsoft Support forums via Neowin