Express.js 4.8.0 Failing

Just installed express 4.8.0. created an app by "express newAp" then "cd newAp && npm install" when I issue "npm start" or "node ./bin/www" or "DEBUG=newAp ./bin/www"

App is not getting started. It's giving error as shown below:

> newAp@0.0.0 start c:\Users\Somenath\newAp
> node ./bin/www


events.js:72
        throw er; // Unhandled 'error' event
              ^
Error: listen EADDRINUSE
    at errnoException (net.js:901:11)
    at Server._listen2 (net.js:1039:14)
    at listen (net.js:1061:10)
    at Server.listen (net.js:1135:5)
    at Function.app.listen (c:\Users\Somenath\newAp\node_modules\express\lib\app
lication.js:546:24)
    at Object.<anonymous> (c:\Users\Somenath\newAp\bin\www:7:18)
    at Module._compile (module.js:456:26)
    at Object.Module._extensions..js (module.js:474:10)
    at Module.load (module.js:356:32)
    at Function.Module._load (module.js:312:12)

Any help would be highly appreciated.

And is there a way I can go back to Express 3.x ?