This is a weird one! A couple of weird suggestions: check the file manifest of the install zip file to make sure your av didn't quarantine a program. This failure is a Fritzing bug which will also occur if I screw up a filename in a new part (so the listed file name doesn't exist). I think the open fail exception doesn't get handled somewhere and frtizing hangs exactly as you describe (although only when I open the new part which isn't the case for you). The other out there suggestion is delete all the directories (the install, and the two user directories) then disable the network connection and do the install with no network connection. This will block the parts update from github, and if fritzing then works that would indicate a new parts update is what is causing your problem (likely because of a missing file). That would at least give us somewhere to look. Other than that I'm pretty much out of ideas!
Peter