Microsoft has issued instructions on how to fix a bug that caused authenticated Windows 7 PCs to be labelled as “not genuine”.

The company revealed the error stemmed from an update to its Microsoft Activation and Validation servers on January 8th.

The problem affected volume-licensed Windows 7 PCs that use Microsoft’s Key Management Service and that had the KB 971033 update installed.

Microsoft reverted the change to its servers after discovering the issue but says admins should additionally remove the KB 971033 update if PCs are still showing the “not genuine” message.

Machines affected by the issue display a “Windows is not genuine” error message after the user logs on and have a “This copy of Windows is not genuine” watermark on the desktop.

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The Microsoft advisory note states “we strongly recommend that you uninstall KB 971033 from all volume-licensed Windows 7-based devices”, whether or not these devices were affected by these latest problems, and full instructions are provided here.

The firm says that KB 971033, an old update, should not have been installed by “an Enterprise customer who uses Key Management Service (KMS) or Multiple Activation Key (MAK) volume activation”, as it was “targeted at consumer installs of Windows using retail activation”.

This isn’t the first issue with Microsoft’s anti-piracy Windows Activation Technologies, which recently caused panic after deactivating legitimate copies of Windows 10.

Microsoft says the issue has nothing to do with the Windows KB 4480960 and KB 4480970 updates, which were also issued on January 8th.

These updates have been associated with a separate bug that blocks administrator access to remote shares on Windows Server 2008 R2 and Windows 7, a problem that Microsoft says it is working to fix.

In recent months, Microsoft has also endured several months of negative headlines about bugs in the latest Windows 10 October 2018 Update, also known as version 1809.

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