I have a virus that deletes all executables of virus software packs. All being deleted during the installation. I have scanned computer online with Norton, Mcafee, and Kaspersky found none. What can be done except restoring the OS and everything.
That deletes only critical executables that you can scan with. This hapened with avast as well.
This case, it is no use to buy an anti virus software, because, I am not able to keep it in computer.