If you're on Linux, this problem can also occur if Nodejs is not running as root.
Change from this:
sudo nodejs /path/to/script.js
Just happened to me and none of the other suggestions here fixed it. Luckily I remembered the script was working the other day when running as root. Hope this helps someone!
Disclaimer: This probably isn't the best solution for a production environment. Starting your service as root may introduce some security holes to your server/application. In my case, this was a solution for a local service, but I'd encourage others to spend some more time trying to isolate the cause.