Clear the cache and the cookies from sites that cause problems. * "Clear the Cache": Tools > Options > Advanced > Network > Offline Storage (Cache): "Clear Now" * "Remove the Cookies" from sites causing problems: Tools > Options > Privacy > Cookies: "Show Cookies" ---- Start Firefox in [[Safe Mode]] to check if one of the add-ons is causing the problem (switch to the DEFAULT theme: Tools > Add-ons > Themes). * Don't make any changes on the Safe mode start window. See: * [[Troubleshooting extensions and themes]] * [[Troubleshooting plugins]]