As described before, see here:
https://community.norton.com/de/comment/8520915
The Problem is now happening again.
This is from today:
This .tmp File is a temporary File from Norton itself.
Firefox does not put any temp-files in this Folder.
I don't know why this is needed, but Norton does it that way.
I guess it would be ok, but since Norton detects its own File as Virus then something is wrong (again).
I thought this was solved....