Just an FYI:

I use PFW, too (on w7, though, not w8). It worked with avast v17.4 without problems. But I downgraded avast for other reasons. And I would never ever ditch any of my software for a bug of another software (in this case avast).

I really get annoyed by this sentiment that if (a new version of) avast is having problems it’s always the other software’s fault. It’s almost never avast’s fault - god forbid!

If the only thing that changed on a system is the version of avast it’s avast’s fault. Period.