I have to admit, I do use Windows! I use it for GSAK, the geocaching database, which it so totally useful, I couldn't do without it. And it needs Windows. But that's all I use Windows for.
Except, in using GSAK, I need to tell it about my two Geocaching.com accounts, so it can access data from them. And I have to give it the authority to do that. But in order to do that, I have to scrub off the login data from the previous one I gave permission for; geocaching.com doesn't really expect me to have two accounts, I suppose.
To scrub off the previous data, I use CCleaner, and I have done for several years. And each time I use it, it offers to update itself, and I say "No thanks".
But if you're a user of Avast antivirus, and got your CCleaner from them, you may have a problem. Avast have accidentally been distributing a trojanised version of their software.