Warning! Master scheduler disabled.

Error
Under the "Run/Schedule" tab in a profile's settings, this error appears under the glowing "Run Now" button:

Cause
The Urchin Scheduler process (urchind) is not running. It's likely that a third party application is killing the urchind process -- please

Resolution
Linux: restart the Urchin scheduler service: /usr/local/urchin/bin/urchinctl -s start

Windows: restart the Urchin scheduler service in the Services Manager