New Kernel Breaks IPFW

Hey everyone,

I just cvsup'd my src today and was going to buildworld later tonight 
but when I installed the newly built kernel with IPFIREWALL etc. and 
rebooted, ipfw fell over, specifically, even after ipfw firewall enable, 
an ipfw show resulted in a core dump. If its useful, I can post the ipfw 
core dump.

Any ideas why this is?

Thanks

-John