Immediately after the release of the April 2019 update by Microsoft, Windows users discovered that Windows 7 and 8.1 started having problems.
Several of them started to "freeze", unable to boot normally and some took too long to boot. This was found to be due to Windows Update conflicting with some software protections from viruses, such as Sophos, Avast and AVG. McAfee was recently added to the list of conflicts.
In some Microsoft articles, last weekteam, regarding the Windows 8.1 update KB4493446 and Windows 7 update KB4493472The company stated that there is a problem with McAfee's security software as well, and it causes the same symptoms, i.e. slow startup or freezing screens.
And while Microsoft says there is an issue with Windows 7 and 8.1 running McAfee software, McAfee claims that these issues also affect Windows 10.
According to McAfee, these problems are due to changes in the service of the Runtime Client Server subsystem, otherwise known as CRSS.exe. And it is not accidental, since the Avast confirms CRSS issues, even giving a solution through the registry.