Windows Update KB3004394, released on 12/10/2014, has been causing issues on some Windows 7 mac hines running Service Pack 1.

When attempting to install devices, the user may encounter an error regarding the signatures for the device drivers (Code 52).

This is an issue with the Microsoft Root Certificate Update, not with your device’s drivers.

Windows Defender has also been reported to stop working, and many users are now receiving UAC prompts unexpectedly.

It may also disable the ability of Windows to download and install future updates. http://support.microsoft.com/kb/3024777

Searching Windows Update for KB3024777 and installing it should resolve the issue, effectively removing KB3004394.

Alternatively, KB3004394 can be manually removed through Programs and Features or through Windows Update in Control Panel.

In any case, the device(s) will need to be uninstalled and reinstalled again after resolving the issue with the patch.