Hmm, that's strange. First, do you use any anti-keylogger software? For example, some versions of ZoneAlarm caused this problem in Firefox in past years: * https://support.mozilla.org/questions/1094562 * https://support.mozilla.org/questions/1008661 Second, can you account for all the add-ons in Firefox? You can view, disable, and often remove unwanted or unknown extensions on the Add-ons page. Either: * Ctrl+Shift+a (Mac: Command+Shift+a) * "3-bar" menu button (or Tools menu) > Add-ons * type or paste '''about:addons''' in the address bar and press Enter/Return In the left column of the Add-ons page, click Extensions. Then cast a critical eye over the list on the right side. Any extensions Firefox installs for built-in features are hidden from this page, so everything listed here is your choice (and your responsibility) to manage. Anything suspicious or that you just do not remember installing or why? If in doubt, disable (or remove). Any improvement?