After reinstalling Firefox yesterday (version 38.0.5) on my computer (Windows 7), I can no longer use Google Voice. I downloaded and installed the Google Voice and Video plugin and also downloaded and installed the Google Hangouts plugin (though I think they are the same). But when I try to make a phone call, it tells me to install the plugin. I have downloaded and installed the plugin MULTIPLE times, rebooted my computer, and restarted Firefox...but it never recognizes that the plugin has been installed. Nor does it appear in my list of plugins.

How can I get this to work? Thanks.