SNMP Polling Problem

Two of our NetVanta 3448 Routers have suddenly started going to nearly 100% CPU Utilization when we enable SNMP polling to communicate with SolarWinds.  It works on the other routers, one of which is also a NetVanta 3448.  Settings all appear to be identical.  The setup worked fine for 2 years............. 

Any thoughts would be appreciated................

Thanks!