mchain
3
Any other antivirus programs previously installed or bundled in when new?
https://singularlabs.com/uninstallers/security-software/
Use the specific vendor removal tool after uninstalling old a/v from Programs and Features (if not already done). Reboot after uninstalling, reboot again after running the vendor tool.
Try a repair of avast. Go to Programs and Features and select avast and click and choose repair. Reboot.
If this does not work, see below:
You may need to run aswclear.exe after uninstalling avast! normally if things are not better after running singularlabs tool rebooting and running a repair. Suggest getting fresh removal/install tools from avast before you remove/install. All work is done off-line (disconnected from the Internet).
https://www.avast.com/uninstall-utility
https://www.avast.com/download-software