Yes, very strange.
I went to Programs&Features, and Avast Browser was installed on Apr 8 2021. I went to my other pc and see the same thing. I'm guessing the browser came down with the virus definitions, because the Avast application is configured "ask when update is available", and I haven't yet updated the application on my 2nd pc. Only the definitions are configured as auto-update.
I started the browser and checked the config. It is *not* configured to be the default, and it is *not* configured to auto-start. After I closed the browser, I now see 26 instances (before was 24) and it now pinned itself to the taskbar.
I remember several times in the past when I updated the application, the browser had made itself the default browser, and auto-start at reboot. After the first time, I went and re-configured both those items to be off, and then the next update, they suddenly were both on again. I remember being annoyed at the time.
On my 2nd pc there are 22 instances of avastbrowser.exe. I guess it's not a big deal, except they do take up memory (up to 100k, some of them), and use some CPU I suppose. And again, I never use that browser, never even opened it.
Now that I installed the update, I'll go ahead and reboot, and see what happens.
Thanks.