The second Tuesday of every month, Microsoft pushes a flurry of updates to all of its supported operating systems. Known as Patch Tuesday in the industry, the updates are supposed to fix known bugs and issues. However, this month's Patch Tuesday updates for Windows 7, specifically KB4493472, aren't playing nice with antivirus software.
In addition to previously known issues with machines running Avira, Avast, AcraBit and Sophos becoming unresponsive after installing the update, McAfee's Endpoint Security Threat Prevention 10.x and Host Intrusion Prevention 8.0 have been added to the list of software that may be incompatible with the update.
The company recently updated the release notes for KB4493472 with the following note:
Microsoft and McAfee have identified an issue on devices with McAfee Endpoint Security (ENS) Threat Prevention 10.x or McAfee Host Intrusion Prevention (Host IPS) 8.0 installed. It may cause the system to have slow startup or become unresponsive at restart after installing this update.
Microsoft has indicated that it's working with McAfee to resolve the issue, but an official fix from either company has no ETA yet. McAfee for its part has confirmed the issues as well, and its Knowledge Base article on the matter indicates Windows 8 and Windows 10 users with Endpoint Security might also suffer from degraded performance or slow boot-up times. The company claims it already has a proof of concept build aimed at fixing the issue available, which it will provide to users who request it.
However, until such a time that an official fix is made available, McAfee recommends users "disable any Access Protection rule that protects a service" as a temporary workaround to circumvent the problem.