OK, but....
1) Avast is very highly rated by independent reviewers, like PC World, and PC Magazine.
2) I still haven't seen any explanation of why Avast trips over Calibre for some of us but not all of us.
It could be an Avast issue, but I suspect there is something in Calibre that mimics malware behavior in some way, which is why I posted here for Kovid. Clearly Calibre is not malware!
And here is my very old but similar thread:
https://www.mobileread.com/forums/sh...d.php?t=253087