I have tried a couple of times clicking on the "Update software" button on the WSAC and have gotten the same message both times. The message was, "You are using the newest version of Webroot and this version no longer needs to update virus definitions. Threat protection is now performed "in the cloud" and is always up-to-date."
So, that being said, why is there an "update software" button? (I know. Dumb question. Right?)