Hi, After some issues I've deleted all Firefox extension, or at least I tried to... There remain two files, one apparently installed by Kaspersky (known to be less of an anti virus software than a virus itself....) the other by Adobe. I've tried everything suggested here: https://support.mozilla.org/en-US/kb/cannot-remove-add-on-extension-or-theme but there never appear the option to "remove" either plugin, nor is the manual uninstall possible - there is no Kaspersky or Adobe file either in "Profiles" or in "Application Support/.../extensions. For the record: I've uninstalled Kaspersky years ago, there should be nothing left of it on my system (though you never know with them). Any ideas...?