Hmm,
I've just done the round on trying different options:
I've tried:
BindAddress: blank, 0.0.0.0, (specific ip)
BindPort: 80, 81, ports below 1024, ports above 1024
Process: starting with forced elevated privileges and without.
Plugins: Just HTTPServer + RenX.Ladder.Web, HTTPServer + RenX.Ladder + RenX.Ladder.Web, HTTPServer + All Ladder Plugins, Variations of previous attemps with and without other plugins.
Im assuming its a bug at this point.