Clear the cache and the cookies from sites that cause problems. "Clear the Cache": *Tools > Options > Advanced > Network > Cached Web Content: "Clear Now" "Remove Cookies" from sites causing problems: *Tools > Options > Privacy > Cookies: "Show Cookies" Start Firefox in <u>[[Safe Mode|Safe Mode]]</u> to check if one of the extensions (Firefox/Tools > Add-ons > Extensions) or if hardware acceleration is causing the problem (switch to the DEFAULT theme: Firefox/Tools > Add-ons > Appearance). *Do not click the Reset button on the Safe mode start window or otherwise make changes. *https://support.mozilla.org/kb/Safe+Mode *https://support.mozilla.org/kb/Troubleshooting+extensions+and+themes This can be caused by corrupted cookies or cookies that aren't send or otherwise blocked. *https://support.mozilla.org/kb/fix-login-issues-on-websites-require-passwords If clearing cookies doesn't work then it is possible that the <i>cookies.sqlite</i> file that stores the cookies is corrupted. Rename (or delete) <b>cookies.sqlite</b> (cookies.sqlite.old) and delete other present cookie files like <b>cookies.sqlite-journal</b> in the Firefox Profile Folder in case the file cookies.sqlite got corrupted. *http://kb.mozillazine.org/Cookies *https://support.mozilla.org/kb/Deleting+cookies

Thanks much. I began following your instructions, but had only the option remove cookies, not show cookies. I didn't mean too, but I ended up removing '''all ''' cookies. This solved the problem for me. However, I don't know how much of a mistake it was to remove all cookies.