Update... It seems like my PC had the first infection in 10-15 years...
I still don't know where it came from, because I didn't install any cracked or strange software, and I din't go online without protection.
It still keeps me thinking why the threat only appeared on this forum an NOWHERE else, but at least it seems to be removed thanks to various Malware scanners and tools.
Sorry if I caused some forum-panic.... Won't do it again