Customers starting ArcMap on new installations of 10.2 may encounter the following error when trying to add the Responder Toolbar.
This is caused by a reference to the creation of the Normal.MXT. If the file isn't created yet Responder will display this error message when attempting to load all the Responder extensions.
As long as the MXT file is already present upon the launch of ArcMap, the error will not present itself. A workaround is to close ArcMap and launch it again and the toolbar will load successfully. This MXT also contains user placement of tools and is sometimes deployed from a system policy which can cause the error to repeat. Future versions of Responder have a remedy in place for this issue already.