system
8
Can you run the specific removal utility for AVG under Windows Safe Mode again?
Do you have “optional” processes active? Disable them.
Any optional device connected? (USB devices, or even ethernet, wifi or any other connection, temporarily disconnect and disable them when you are about to run the setup.exe for Avast).
Any other security tools active, or installed (but inactive), or that were seemingly uninstalled before?
Are you downloading the installation setup.exe for Avast ANEW from the official site?
After you download the setup.exe, right click on it → properties → “unblock” → OK.
Then right click → “Run as Administrator”.
Please report back, specially including answers to the above questions.