Does this appear all the time or only on certain pages? Often extraneous bars are generated by add-ons. Could you try disabling all of your extensions (except for the handful you absolutely cannot live without) and try that for a day to see whether it helps? Or if you want someone to scan your extension list, you could post it here. * Disable or remove extensions here: orange Firefox button ''or'' classic Tools menu > Add-ons > Extensions category * Copy and paste extension list from here: Help > Troubleshooting Information (second table on the page; don't worry about the hideous formatting when you paste)