Clear the cache and the cookies from sites that cause problems. "Clear the Cache": * Tools > Options > Advanced > Network > Offline Storage (Cache): "Clear Now" "Remove Cookies" from sites causing problems: * Tools > Options > Privacy > Cookies: "Show Cookies" ---- Start Firefox in <u>[[Safe Mode]]</u> to check if one of the extensions or if hardware acceleration is causing the problem (switch to the DEFAULT theme: Firefox (Tools) > Add-ons > Appearance/Themes). *Don't make any changes on the Safe mode start window. *https://support.mozilla.com/kb/Safe+Mode