I've tried changing DNS servers to OpenDNS's, I've cleared my history and website data from Safari, and I've uninstalled all extensions… but the browser just won't load Gmail! Whether I click on Sign In at
google.com or enter gmail.com in my address bar, the page just never loads.
Not sure if related, but when I try visiting YouTube, Safari says the certificate is invalid. I click to proceed anyway, and the page automatically redirects to
https://ad.doubleclick.net/N6762/adi/mkt.ythome_1x1/;sz=1x1;tile=3;ssl=1;dc_yt=1;kga=-1;kgg=-1;klg=en-gb;kmyd=ad_creative_3;ytexp=931369,937426,900245,902410,924645,946201,936112,9405772;ord=1426347126252949? It's a blank page. What's up with the auto-redirection? When I try to visit youtube.com again, I get served a site with no stylesheet or images.
google.com loads without a problem although Safari throws up the invalid certificate warning as well.
Gmail loads fine on the Safari-only guest account, if it helps. My hosts file is ok. I'm using OS X 10.10.1 and Safari 8.0.2.