Does it matter whether you use www? Will the sign-in link open: https://signup.netflix.com/#do-login When you have a problem with one particular site, a good "first thing to try" is clearing your Firefox cache and deleting your saved cookies for the site. 1. Bypass Firefox's Cache Use Ctrl+Shift+r to reload the page fresh from the server. Any difference? If not... 2. Clear Firefox's Cache Completely orange Firefox button ''or'' Tools menu > Options > Advanced On the Network mini-tab > Cached Web Content : "Clear Now" 3. If needed, remove the site's cookies in this dialog While viewing a page on the site, right-click and choose View Page Info > Security > "View Cookies" Then try reloading the page. Does that help?