NPM and Grunt throwing error and I can't get around it

So I'm starting to work with Grunt and NPM for a project. I was able to set up and run Grunt successfully. Then if I try to install a new plugin with NPM, I get this error:

module.js:338
throw err;
      ^
Error: Cannot find module './config/core.js'
at Function.Module._resolveFilename (module.js:336:15)
at Function.Module._load (module.js:278:25)
at Module.require (module.js:365:17)
at require (module.js:384:17)
at /usr/local/Cellar/node/0.10.20/lib/node_modules/npm/lib/npm.js:19:15
at Object.<anonymous> (/usr/local/Cellar/node/0.10.20/lib/node_modules/npm/lib/npm.js:467:3)
at Module._compile (module.js:460:26)
at Object.Module._extensions..js (module.js:478:10)
at Module.load (module.js:355:32)
at Function.Module._load (module.js:310:12)

I then search around and see suggestions to do a npm install again. Or even an npm update. The problem is I get the same error! I even try doing things globally and in the root folder and I still get the error :(

Would greatly appreciate any help on my issue

Here is my Gruntfile.js

module.exports = function(grunt) {
    require('jit-grunt')(grunt);

    grunt.initConfig({
        less: {
            development: {
                options: {
                    compress: true,
                    yuicompress: true,
                    optimization: 2
                },
                files: {
                    "css/style.css": "less/style.less" // destination file and source file
                }
            }
        },
        watch: {
            styles: {
                files: ['less/**/*.less'], // which files to watch
                tasks: ['less'],
                options: {
                    nospawn: true
                }
            }
        }
    });

    grunt.registerTask('default', ['less', 'watch']);
};

Here is my package.json

{
  "name": "showtime",
  "version": "0.0.1",
  "main": "Gruntfile.js",
  "dependencies": {
    "grunt": "~0.4.5"
  },
  "devDependencies": {
    "grunt": "~0.4.5",
    "grunt-contrib-less": "~0.11.0",
    "grunt-contrib-watch": "~0.6.1",
    "jit-grunt": "~0.7.0"
  },
  "author": "Amie",
  "license": "BSD-2-Clause"
}