Do you consider CCleaner would have reported computer misbehaving merely for a file being stored in Avast (maybe in quarantine)?
avast quarantine is a protected area, no program other then avast has access to it
It seems that CCleaner perhaps detected a malicious file that Avast had not been able to delete but had put in quarantine.
CCleaner is not a security program, it does not detect malicious files
had not been able to delete but had put in quarantine.
[b]What Does Quarantine, Delete, and Clean Mean?[/b] https://www.lifewire.com/clean-quarantine-or-delete-3972276