RIP does not add route entrys after periodic PPPoE reset

[Gerinsel]

In the system log, there is error "routed[12915]: setsockopt(IP_ADD_MEMBERSHIP RIP): Invalid argument" an no route updates are propagated or received any longer.
Is there any workaround or solution?

Edit:
The process seems to running, but the routing table does not show any learned route entry anymore.
The process itself is sending out routing updates which are received by other routers.