Good morning!
I just partially solved the problem. I have already started by deactivating / activating each plugin, one by one, without conclusive result. I then looked in the Firefox developer command for all the error messages and looked at each message one by one. I found, after multitudes of google searches, that some webmasters had problems displaying Google ads because of what is called MooTools. So I installed DJQueryMonster (plugin to disable MooTools) and obviously the Google translation works again. On the other hand, I manage to have the drop-down menu in CB-Login only when I am offline (and not online). Currently I'm in the testing phase because I'm afraid that DJQueryMonster will prevent other plugins from working...