Yes, restart, and even reboot.Have you restarted devfs? Are the permissions actually as they need to be on the device?
% ls -l /dev/bpf*
crw-r----- 1 root wheel 0xe Apr 11 21:39 /dev/bpf
lrwxr-xr-x 1 root wheel 3 Apr 11 20:28 /dev/bpf0 -> bpf
own bpf root:wheel
perm bpf 0640