Virus on My Mac that keeps coming back after clean install.

+3 your "virus" is that you installed Avast, and Objective-See which at best are 100% worthless. At worst (which is what you are seeing) they do the exact opposite of what users want, they make Mac OS slow, unstable, appear buggy and cause unwanted effects just like what you are experiencing. In return they do absolutely. nothing that Mac OS cannot do on its own! All that Mac OS needs to remains secure, fast and trouble free is simply to keep it up-to-date and restart the computer about 1x per week. Other than that just enjoy it and leave it alone!!

Please locate the developers uninstall instructions for Avast, and Objective-See and follow to the letter. After you have executed them, please restart the computer in Safe Mode and then restart normally. To see if you have completely uninstalled Avast and Objective-See run a fresh EtreCheck report and analyze it to see if ANY remnants of either apps are present. If they are, post back and we can provide instructions.

Please remember that Mac OS is NOT MS Windows, so please don't treat it like it is!

your main issue that I see is that you have "multiple" antivirus apps installed. antivirus apps, as well as apps that claim to "speed up" or "clean up" or otherwise "optimize" your Mac are neither needed nor recommended. the only thing they are good at are consuming system resources while providing ZERO protection or benefit. you would do well to uninstall them using the developer's instructions.

and also please note that antivirus apps on a Mac are known to show problems where no problem exists so that the user thinks the app is doing it's job.

"It," whatever it is, keeps coming back because you installed things that are a) tripping over each other and b) causing problems themselves.

I understand your apparent desire to protect your Mac, but what you have is not just overkill, it's also unnecessary and is often the source of problems.

Remove all the following:

Avast

Objective-See

MacCleaner (all components)

I would add that Macs can not get a virus. (Malware, yes) I also strongly second what jeffreythefrog said.

Anti-virus apps are notorious for false reporting.

Some "cleaning" apps are notorious for identifying important MacOS components as "bad" and deleting them. Dead Mac.

Please do not fall for "fear" marketing. Apple have included elegant automated self- maintenance routines as an integral part of the Mac OS going back as far as the start of OSX in 2000. They even defrag if needed. They need NO outside help.

You have multiple antivirus products installed that are likely colliding on the same files when those files are accessed - Avast in particular ought to go.

MacCleaner is a poorly designed product that often deletes caches and other components that macOS uses to improve performance (the whole point of a cache).

Your computer is vintage and you have a fusion drive - which for the purpose of downloading/buffering streaming video, probably means you have a mechanical hard drive. If you really want to know how bad that is, run Etrecheck while you are streaming audio/video and experiencing the distortions.

There is nothing to indicate malware.