Now that you have SP3 installed, reboot and read again the complete topic. Follow the instructions again to remove ALL remnants of ALL older security tools you ever HAD.

Then run the removal utility for Avast.

Better yet, run the removal utilities (for Avast and for older security tolls) under Windows Safe Mode so to reduce potential conflicts.

Then install Avast ANEW, with a new download of the latest stable Avast version.

Once installed, reboot immediately and only then configure it, update the latest definitions and so on.

Please report back.