Ran into this the other day. A 2801 router running IP Base 128M ram. Running EIGRP routing protocol. When we enabled multicast routing and IP pim sparse-dense-mode on the interfaces, within 5 minutes the telnet connection drops and we are unable to ping the router except from the directly connected interface, and cannot telnet into the router at all. Eventually we will get eigrp timeouts and resets, and then no longer able to ping the router. When we remove multicast, routing returns to normal. We changed the IOS to SPSERVICES of a known good image that we run on other routers just fine. Searching the Cisco site came up empty. There are no logs or anything to look at, and CPU/Memory was OK. We dont have access to the console unless we dispatch someone out, so troubleshooting this has become a pain. Any Ideas where to go from here? Can this be a hardware issue? Only card installed is a WIC-1DSU-T1-V2 card.