ENOTFOUND error while installing 'express' in Node.js - Windows

I'm trying to install express package of Node.js through my Windows 7 CMD.

I did a

npm install express

and I'm getting the following error :

npm ERR! Error: getaddrinfo ENOENT
npm ERR!     at errnoException (dns.js:31:11)
npm ERR!     at Object.onanswer [as oncomplete] (dns.js:140:16)

and

 npm ERR! cwd D:\node
    npm ERR! node -v v0.6.15
    npm ERR! npm -v 1.1.16
    npm ERR! syscall getaddrinfo
    npm ERR! code ENOTFOUND
    npm ERR! message getaddrinfo ENOENT
    npm ERR! errno {}
    npm ERR!
    npm ERR! Additional logging details can be found in:
    npm ERR!     D:\node\npm-debug.log
    npm not ok

I'm working behind a Firewall. Is that by any chance, the reason behind this?

Many thanks!