I have the same problem.
When I open the map it is suddenly a secure connection. This means that the Garmin communicator plugin is not working. When I click a cache on the map en ask to send it to my GPSmap 62S I got the message that the plugin is not unlocked.
All other pages pages in Geocaching.com give no problem uploading a cache.
How can I change it.
I have this problem with Win 7 + Google Chrome/Firefox and Win 8.1 + Google Chrome/Firefox/Explorer11.