This sounds similar to what I have seen on my VMWare — not exactly, but similar.
I was seeing lots of dropped port 137 traffic for addresses in the 192.168.x.x range, and thought we had a misconfigured PC on our network with some default IP address. I finally realized that VMWare configures a couple of virtual network adapters in Windows using the 192.168.x.x private range for its virtual networks. The rogue PC was mine!
This broadcast traffic was being sent out all of the adapters (real andvirtual), and the server was trying to respond, but it was going to the gateway on our network (firewall/router) and was being dropped. As soon as I disabled the virtual adapters in Network Connections, the dropped traffic stopped.
I’m not sure if the port 80 traffic you are seeing is in the same vein or not. Hope this helps a little.