I upgraded to .NET 4.5, now SignalR seems insistent on using WebSockets in Firefox/Chrome - even though I\'m only on Windows 7 which doesn\'t have a WebSocket Server.
I found the answer here:
https://github.com/SignalR/SignalR/wiki/SignalR-JS-Client
Basically:
$.connection.hubs.start({ transport: 'longPolling' }, function() { console.log('connection started!'); });