It opens without any apparent issue here. You could try clearing the cache then deleting Cookies. Use the Inspector (ctl+shft+i > the Storage tab) to clear cookies. If that doesn't work, try right-clicking the site in History then ''Forget about this site''. Make sure you have a backup record of your user name and password before doing that because they will be forgotten also. https://support.mozilla.org/en-US/kb/how-clear-firefox-cache https://support.mozilla.org/en-US/kb/clear-cookies-and-site-data-firefox https://support.mozilla.org/en-US/kb/delete-browsing-search-download-history-firefox#w_remove-a-single-website-from-your-history ---- If none of those fixes the issue, try restarting in troubleshoot mode. https://support.mozilla.org/en-US/kb/diagnose-firefox-issues-using-troubleshoot-mode https://support.mozilla.org/en-US/kb/troubleshoot-extensions-themes-to-fix-problems (also deals with hardware acceleration) https://support.mozilla.org/en-US/kb/troubleshoot-issues-related-to-add-ons