Comment 11 for bug 376760

> "While trying to retrieve the URL: http://127.0.0.1:36146/?"....
> I've discovered a workaround:
The actual problem with my configuration was that Firefox obviously can't handle an entry like '127.0.0.0/8' in the proxy exception list when importing system proxy settings from gnome.
After manually adding 127.0.0.1 explicitly in the gnome proxy settings and restarting firefox, it worked. That's basically similar to Kev's workaround, because localhost of course is in the exception list.