Thanks for using the answers forums. The colored lights next to your Slingboxes in the directory tell you about the status of your Slingbox. A green light means that it is configured and ready, a red light means it is being used, and a yellow/orange light means that the Slingbox is not configured and needs to be be set up. You can use the website setup.slingbox.com in the location of the Slingbox PRO-HD to set it back up.
Hope this helps,
The Sling Moderation Team