Just to rule out an issue with Windows, your router, or your ISP: does it work in IE? Did you disable plugins by testing in Firefox's Safe Mode? If not, you might try that. First, I recommend backing up your Firefox settings in case something goes wrong. See [https://support.mozilla.com/en-US/kb/Backing+up+your+information Backing up your information]. (You can copy your entire Firefox profile folder somewhere outside of the Mozilla folder.) Next, use Help > Restart with Add-ons Disabled to restart Firefox in Firefox [http://support.mozilla.com/kb/Safe+Mode Safe Mode]. Don't check any boxes in the Safe Mode dialog, just click the "Continue in Safe Mode" button. Does the login work in Safe Mode? If so, it could be one of your add-ons, or it could be another setting or saved login that has become corrupted.