Kent,
     You need to go to the Cisco web site ( www.cisco.com ) and read the
article

"IP Simple Network Management Protocol (SNMP) Causes High CPU Utilization"

     It talks about the problem related to network management systems doing
snmpwalks on low end routers and acting exactly like you are describing
them.

     To find it, I just searched on "High Router CPU" and it was the first
item on the list.  It tells you how to configure your routers to avoid the
problem.

          Good Luck,
          Bill