As for resident antiviruses I would generally agree (even for purely logical reasons - that means adding another 3-rd party to the 100% trusted list, you grant their app godlike access to your computer and everything on it and let it talk freely and secretly to their vendor), nevertheless a live-cd version of something like Dr.Web can be of great use in such cases, Windows Defender a well as other antiviruses ran under an infected system can often be futile against viruses infesting it. Perhaps open-source ClamAV can do the job too but I'm not sure.