node.js Error Cannot find module 'optimist'
===

I had upgraded the node to v0.6.18
Then I started using the meteor.
Whenever I use any command related to meteor I got an error. 

node.js:201
        throw e; // process.nextTick error, or 'error' event on first tick
              ^
Error: Cannot find module 'optimist'
    at Function._resolveFilename (module.js:332:11)
    at Function._load (module.js:279:25)
    at Module.require (module.js:354:17)
    at require (module.js:370:17)
    at /usr/lib/meteor/app/meteor/meteor.js:596:18
    at Object.<anonymous> (/usr/lib/meteor/app/meteor/meteor.js:632:1)
    at Module._compile (module.js:441:26)
    at Object..js (module.js:459:10)
    at Module.load (module.js:348:32)
    at Function._load (module.js:308:12)

In order to solve this issue I used 'npm install optimist'.
It has installed successfully. But it didn't solve my problem.
Please suggest some solution to this issue.