The Garmin Communicator Plug-In 4.1.0.0 shows in the System Details list next to the question as an installed plugin. *https://support.mozilla.org/kb/Troubleshooting+plugins Isn't this about a message from that plugin? Has there been an update for that plugin recently? Try to disable multi-process tabs in Firefox to see if that has effect. You can disable multi-process tabs in Firefox by setting the related prefs to false on the about:config page. *browser.tabs.remote.autostart = false *browser.tabs.remote.autostart.2 = false You can open the <b>about:config</b> page via the location/address bar. You can accept the warning and click "I'll be careful" to continue. *http://kb.mozillazine.org/about:config