NCM Triggers SNMP Protocol Violation on Cisco IPS

I have a lrge number of alerts from my Cisco IPS (runing signature 867.0). They are all showing my NCM/NPM server as the attacker. The message is high 4507-6 SNMP Protocol Violation (<IPS HOST NAME>).

   sig_id = 4507

   sig_name = SNMP Protocol Violation

   sig_version = S751

   attacker_ip = xxx.xxx.xxx.xxx

   attacker_port = 59121

   attacker_locality = OUT

   victim_ip = xxx.xxx.xxx.xxx

   victim_port = 161

This signature has a reliability rating of 100. That means there are no known false positives.

Has anyone experience of this and what may be causing it?

John

Orion Platform: 2015.1.0

NCM: 7.3.2

NPM: 11.5

Operating System: Windows Server 2008 R2