Avast on Mac Infection blocked from website not visited after clean build

I am getting a pop-up regularly when using safari thats says Infection blocked from some website I have never visited. It happens when I open different sites, google, facebook so not limited to any one website.

My wife has a Mac and I have rebuilt both together from scratch and hers never does this.

I have rebuild mine again after a HDD erase and rebuild with High Sierra.

I can’t see how I can load the jpg of the popup so here is the text.

Infection URL:MAL
URL. : http:www.stafaband.info/download/mp3
Process: /System/Library/Frameworks/Webkit.framework/Versions/A/XPCServices/com.apple.Webkit.Networking

any ideas as I am at a loss as to what to do next

Hello,
the URL was unblocked.

Milos