%NHRP-3-PAKERROR:

[psymonds7769]

Can anyone point me to a resource to determine possible root causes of this error message:

%NHRP-3-PAKERROR: Received Error Indication code:  loop detected(3),

[MHM Cisco World]

are you config ip nhrp responder ?

[psymonds7769]

No.  We basically use NHRP in a DMVPN setup, 2 Cisco 1111 devices at the same site with tunnels sourced off Gig interfaces to the primary ISP

[MHM Cisco World]

So your router C1111 is spoke, 
I think the Hub is config ip nhrp responder 
and since C1111 is spoke you must config same IP hub use as responder in ip nhrp nhs. 
check this point

[Georg Pauwen]

Hello,

can you post the full configs of the hub and the spoke routers ?