Somehow this only happens following the bootup, it attempts to download an update, probably succeeds and then crashes the PC while displaying a checkerboard. Then after restarting Avast has already partially updated and requires restart to activate its shields. And mind you I’m using Manual Updates.
On another thing, it upsets me Avast no longer has selective silent mode, in that you either set all notifications (including offers) on, or none of them at all.
Silent mode is your choice because you don’t want to see any popups.
The alternative is to purchase the product. I’m sure Avast is well aware of that action of silent mode.
In the past, it used to at least bring up update notifications (as they were most important) while hiding all else, plus it used to open a “quick scan” window if they user initiated a scan via Windows Explorer, and now it does not. That is however beyond the scope of the issue: something is causing the checkerboarding to happen, and both times it happened it was connected to Avast somehow.