starting Fiddler stops a running docker process.
stopping Fiddler shuts docker demon down completely.
docker version: 17.09.0-ce
Mono version: 5.4.201
Fiddler version: Beta downloaded 31-Oct-2017
Macos version: Sierra 10.12.6
Workaround: start docker process after starting Fiddler
Let me know if there's anything I can do to support investigation.