I've recently seen this problem on a second server, on totally separate networks.
Webroot stops communicating with the web console. On one machine this manifested as Webroot showing the subscription was expired. On another machine the symptom was that the agent was shown with a status of 'Not Seen Recently' in the console
The fix for both of these was to Install the Starfield Class 2 Certificate into the Trusted Root Certification Authority store on the machine and bingo - comms restored.
As I've now seen this on a second server I'm concered this could be a wider issue. Has anyone else seen this or have further information?