Windows updates break PCs with these antivirus programs

On April 9, Microsoft released a Windows patch that fixes PCs that have some antivirus programs installed. This concerns PCs running Windows 7, 8.1, Server 2008 R2, Server 2012 and Server 2012 R2 – not Windows 10, this time.

After the update is installed, you will not be able to log in to Windows if you have anti-virus software installed on your system. Windows will shut down once you have logged in.

This issue affects PCs with Sophos antivirus software, Avira, Arcabit, Avast, and McAfee. Microsoft has continuously added antivirus programs to this list and McAfee is the latest. To protect users, Microsoft has added a block to this update that prevents it from being installed on PCs with the relevant antivirus software.

If your PC has actually installed the update before Microsoft has crashed, you will probably need to install an update of your antivirus software to fix the problem. Microsoft provides more information on these known issues on its website.

It seems that Microsoft has modified CSRSS (client-server runtime) in this update. This change is causing problems with some antivirus software.

Of course, not all antivirus software is affected. We love Windows Defender (Microsoft Security Essentials for Windows 7) and Malwarebytes. Neither one nor the other is having problems with this update.

Thanks to Ars Technica and PCWorld for putting the spotlight on this topic.