This looks like an error on the IPython side, not in in Julia. If you just run "ipython notebook" to open a Python notebook (not IJulia), does it work?
(Be aware that running a firewall on your machine may break the IPython notebook. e.g. for the Sophos <https://en.wikipedia.org/wiki/Sophos>endpoint security software, go to "Configure Anti-Virus and HIPS", select "Authorization" and then "Websites", and add 127.0.0.1 to "Authorized websites"; finally, restart your computer.)
