Samba and "BAD-TRAFFIC 0 ttl" alerts

[<hugh_fraser () dofasco ca>]

I've been seeing a lot of "BAD-TRAFFIC 0 ttl" alerts recently, from port
137 to port 137 on the subnet broadcast address. It appears to be coming
from nmbd running on RedHat Enterprise Server. According to the RFCs,
sending a packet with a 0 ttl is invalid, but I cannot see anything in
the Samba config that would cause this. There are plenty of references
to WINS ttl values, but nothing about IP. Is this normal behaviour for
Samba, the result of mis-configurations, or an indication of something
more sinister?