Pale Moon, which is a fork of Firefox (you can see it as a Firefox 25 with security patches). But I already had this problem when I was still using Firefox.
How is it managed at very first connection? I have several "blockers" installed (anti-ads, anti-cookies, anti-trakers and some more ): one of them is certainly the cause the problem, as everything seems indeed to work when using Midori or even Firefox (with all addons deactivated).