Hi,
If still the issue persists, try to do a clean installation from the scratch..
Download the uninstall utility from the
http://files.avast.com/files/eng/aswclear.exe link and save it.
To remove the currently installed avast!, Open avast! GUI, click on Settings (on top right corner) -> Troubleshooting -> Uncheck "Enable avast! self-defence module" and click on OK.
Run the aswclear.exe utility to remove avast! from the machine.
OR
Try boot into Safe Mode and run the removal tool.
Once you remove the avast!, make sure that you reboot the machine.
Download the latest version of avast! product that you have purchased and install it.
Try now to scan the files and please update back regarding the beep sound.
Have a wonderful day. Good Karma!