As of this morning these include Windows 7, Windows 8.1, Windows Embedded 8, Windows Server 2008, Windows Server 2012, Windows Server 2012 R2 and Windows 10. Unfortunately, it would appear that a broad sweep of Windows versions are affected by the update problems.

So it seems there is a combination of freezing/locking up during the update installation process itself, boot-looping and locking after the update and systems becoming sluggish and unresponsive if they do start successfully.

Microsoft has confirmed that there is 'an issue on devices with Sophos Endpoint Protection installed and managed by either Sophos Central or Sophos Enterprise Console (SEC) that may cause the system to freeze or hang upon restart after installing this update.' Users of Avast for Business and CloudCare have been reporting machines locking up on startup and Avira antivirus users are suffering from Windows running very slowly.