It disables some graphics driver updates, as well as Windows Defender
As a general rule of thumb, I’m a proponent of setting Windows Update to automatically updating the OS (operating system) an Office products. But, in this particular case, accepting/applying one particular update, specifically KB 3004394, can cause a range of serious problems and I recommend (as does Microsoft) removing it.
The first issue that caught my attention is that KB 3004394 blocks the installation or update of graphics drivers such as AMD’s new Catalyst Omega. Nvidia users are also reporting difficulty installing GeForce drivers. Hallock recommended manually uninstalling the update, advice now echoed officially by Microsoft.
The issues related to this newest update isn’t limited to graphics driver problems. Redmond hasn’t directly divulged each and every issue, but Microsoft’s Answer Forum is littered with tech-savvy users reporting that USB 3.0 drivers are broken and User Account Control (UAC) prompts have gone haywire. Microsoft has acknowledged that it may even prevent the installation of future Windows Updates.
An even more troubling byproduct of this update is that the Windows Defender service, which is crucial software that blocks viruses and malware, has even been disabled by the update.
It’s important to note that only Windows 7 and Windows Server 2008 R2 have have issues with this update. .