Your ccleaner automatically removes items in Avira's quarantine directory when "AntiVir Desktop" is checked under applications. I don't believe this should be done, or at least should be optional. Items are placed in quarantine so they can be evaluated, and might be something desired or necessary that might later have to be restored.
Can you not protect that folder with the Options / Exclude / Files and Folders to exclude ?
Alan
Yes. but since I wasn't aware that Ccleaner was erasing that data, I have already lost something I really wanted to keep. Thus my suggestion - either don't clean that subdirectory at all, or at least have it as a checkbox option under the "AntiVir Desktop" application.
AntiVir self-protects many of its files unless you configure it to disable the protection which is never recommended. So I'd say just remove the Avira Desktop cleaner altogether especially for quarantined items as already outlined as something could be a false positive and need to be restored.
In the meantime you can just untick AntiVir Desktop and CCleaner won't offer to clean it, which is what I've done.