Well, it was remembering the exceptions I >had< made in the past, but now it's empty.
The only thing that's weird is the zip file stuff. I've never seen that before, and I don't understand what-the-**** it's doing there. There is no more zip file, the contents have been extracted and installed.
Anyway, I've disabled the sandbox thing. I never used it, don't see it's purpose, don't know what the effect of using it would be, etc. Problem solved.