multicast group memberships exceeded in FreeBSD 6-Prerelease

[Nik]

Mar 5 18:15:42 pjdist ospfd[82930]: can't setsockopt IP_ADD_MEMBERSHIP (fd
6, addr 202.552.36.36, ifindex 17, AllDRouters): Too many references:
can'tsplice; perhaps a kernel limit on # of multicast group
memberships has been
exceeded?
Mar 5 18:15:42 pjdist ospfd[82930]: can't setsockopt IP_ADD_MEMBERSHIP (fd
6, addr 202.552.36.1, ifindex 18, AllDRouters): Too many references:
can'tsplice; perhaps a kernel limit on # of multicast group
memberships has been
exceeded?

I'm sorry because I did paste the wrong error message. It's seem my system
need some patching as what you said. Please help me to solve this problem.
Forget to mention that I'm using quagga 0.99.3 on FreeBSD 6.0.

As I mention in my first email, I haven't patching unix system before so I
am really appreciate if you can lead me how to do it. Thanks a lot.