As mentioned, unless you did a clean reinstall of avast 8, then the old avast5.ini data will remain in place and it was that which contained the instruction to insert the clean notes.
Unfortunately having removed the UI selection to insert (or reverse) the clean note, there is no easy way to remove it, you would have to edit the avast5.ini or do a clean reinstall of avast 8.
If you want to do the edit of the avast5.ini let me know and I will show you how.