On my Packard Bell(my wife's laptop) with Windows Vista Home Premium(licensed):
I had Avast Internet Security 2018 installed(licensed).
Sleep and Hibernate did not work.
I maked the steps you indicate for clear avast.
After clearing Avast with AvastClear.exe, Sleep and Hibernate are working again.
But, wait, after complete installing, Sleep and Hibernate don't work... Display is black but the hard disk continue to show activity.
Please, help me. It's about my wife...
PS. It's very clear, Avast Internet Security is creating this problem.
I know, Packard Bell Easynote Me35, Windows Vista... oldies.