Starting with version 10.6.1 the web interface will pop up an alert box before performing an action that could interrupt network traffic. To turn this feature off in the web interface navigate to Web Options.
There are two levels of alerts that can configured, Show major disruptions and Show feature disruptions. 'Major' disruptions are actions that can affect all traffic passing through the Ecessa device. A 'feature' disruption means that only traffic releated to the feature being changed will be interrupted. Unchecking both of these boxes will disable all warnings.
For more details of what actions can cause traffic disruption see the article What actions will interrupt or disrupt traffic?