The people saying Avast isn’t causing this is in denial. I work with computer repair and I’ve been noticing it happen ever since Windows 10 came out and sometimes the issue appears immediately after installing Avast or after rebooting it once Avast is installed. Uninstalling Avast fixes of the problem every single time.

Of course if you’ve been dealing with Windows 10 for long enough you know that there are a number of things that break the start menu and cause the desktop shell to stop responding (outdated shell extensions for example), but that doesn’t mean Avast isn’t causing it too.

Oh btw this is after performing a clean install of Windows 10 on many different systems.

Just today I experienced something similar after installing avast on a Windows XP machine. Right after installation and before the “Welcome to avast” audio was played the desktop shell stopped responding, I was still able to use the mouse and interact with open Windows’ but nothing else worked. I’ve seen this happen on Windows 7 as well, more than once, and although it only happened after finishing the installation and didn’t happen again after rebooting the computer (avast worked fine after reboot) it’s very similar to what happens on Windows 10 the only difference being that on Windows 10 it can happen at any time and not just when the setup completes and before the Avast UI is able to start.