I'm trying to install the FireFox extension of 1Password but everytime I try I get the following error:
Firefox (profile name: default) is running.
We cannot install our Firefox add-on while Firefox is running.
Please close the existing Firefox process, and try again.
However, Firefox is definitely not running. I've checked task manager and have rebooted, etc. It just refuses to install. However, the Internet Explorer add-on and Google Chrome extensions both work fine. I've also upgraded Firefox from an older version to the latest (not sure which version) and it still just won't install.