Your PBX is Offline

When applying a backup to a system, where the backup contains configuration for the t1/e1, you may receive this error: Your PBX is currently offline. Click to view.

When you click the link, it opens up the Channel Groups page that displays the following:
 

( ! ) Your configuration is incorrect and your phone system is now offline.
Please correct the errors below immediately to resolve this problem.

This issue is easily resolved in most scenarios.  What is happening is that the PBX sees your card multiple times.  This is commonly corrected using the following KB: 
Telephony Card Appears Twice in Switchvox