freebsd stable - Apr 2003 - VS: 4.8-STABLE Kernel Panic with dummynet options.

I first saw this problem when our internetgateway refused to boot its new
kernel, it was a 4.7-RELEASE. Then i loaded the old kernel and went home to
check if my 4.8-STABLE does likewise. And the answer was yes! Both kernels
were GENERIC + these options taken from the dummynet man pages:

options         DUMMYNET
options         NMBCLUSTERS
options         HZ

When i boot the machine it suddently reboots when the kernel starts loading,
i can just manage to see something about "panic: mbinit" before it
reboots.

Both systems are i386.
I hope any of you can tell what's wrong, i really need this feature.

Regards,
Johan Christiansen
HazarT Consult
Denmark.