A Windows Update released for March’s Patch Tuesday may be causing a reboot loop as Windows 7 computers alternately apply the update and revert the changes. The code signing update KB 3033929 has been indicated as the problematic update. KB3033929 brings SHA-2 code signing support to Windows 7 and Server 2008 R2. The update was previously released in October 2014 as KB 2949927 but was recalled after problems arose then.
One theory states that since the update adds SHA-2 signing and signature verification, the computers having issues with this month’s update may already have something installed with a bad signature.
Security Update for Windows 7 for x64-based Systems (KB3033929)
Installation status: Failed
Error details: Code 80004005
Update type: Important
A security issue has been identified in a Microsoft software product that could affect your system. You can help protect your system by installing this update from Microsoft. For a complete listing of the issues that are included in this update, see the associated Microsoft Knowledge Base article. After you install this update, you may have to restart your system.
It is recommended for those manually installing the updates to install KB 3035131 first and then install KB 3033929.
From KB 3035131:
If you manually install the security update that is described in advisory 3033929 and then manually install security update 3035131, you receive a message that states that update 3035131 is already installed. In this scenario, security update 3035131 is not added to the list of installed updates. Update 3033929 includes the security updates that are provided by update 3035131. Therefore, the system is not in an unprotected state in this scenario, even though update 3035131 is not added to the list of installed updates. Customers who plan to manually install both updates are advised to install the 3035131 update before they install the 3033929 update. If customers manually install the updates in this order, the list of installed updates will include both updates.
Despite installing the updates in the correct order, the problem appears to be impacting multiple people reporting the issue on Microsoft forums and HP forums. So far, Microsoft has been quiet on the reported problems with this release and has not yet released a fix, though it seems to be a smaller footprint than the previous attempt.