Thanks for trying to help, but the posted solution doesn’t work.
The solution states:
HKLM\SYSTEM\CURRENTCONTROLSET\CONTROL\Session Manager

on the right there will be a key labeled “BootExecute”

Doubleclick that key and you should see at least the default value of “autocheck autochk *” which is scandisk. Somewhere below that should be the path to avast (Alwil Software) with options (sorry I can’t tell you what they would be or what the line will look like, bit i don’t know however it should be obvious that it is avast) but anyway delete that entire line and you won’t see it again.

However, all I get is “autocheck autochk *” and there is nothing below that line.

This has only started since the last program update on Jan 21