NPM can't install appjs. Error: Cannot find module 'graceful-fs'

I installed node.js and npm already, but when I try to install appjs I get this error:

zephlon@zephlon-T5254:~$ npm install appjs

node.js:201
    throw e; // process.nextTick error, or 'error' event on first tick
          ^
Error: Cannot find module 'graceful-fs'
    at Function._resolveFilename (module.js:334:11)
    at Function._load (module.js:279:25)
    at Module.require (module.js:357:17)
    at require (module.js:368:17)
    at Object.<anonymous> (/usr/share/npm/lib/utils/ini.js:32:10)
    at Module._compile (module.js:432:26)
    at Object..js (module.js:450:10)
    at Module.load (module.js:351:31)
    at Function._load (module.js:310:12)
    at Module.require (module.js:357:17)

I get similar errors on any attempt to install graceful-fs.

I am using Ubuntu 12.04 LTS.

P.S.: Here's the link to the appjs website: http://appjs.org/