"npm install -g ionic" hangs on "unlock" step


I tried to install ionic on Windows 7 machine as follows:

npm install -g cordova

which went well, so I continued with this:

npm install -g ionic

but it hangs. So I stopped it, removed it and tried again with –verbose flag, but no success. Tried also -ddd flag, but still hangs. Step on which it hangs is:

npm verb unlock done using C:\Users\myusername\AppData\Roaming\npm-cache\_locks\npm-7933e7d5b0e47ece.lock for C:\Users\myusername\AppData\Roaming\npm\node_modules\ionic\node_modules\ionic-app-lib\node_modules\ionic-cordova-lib\node_modules\npm

Any clues? I’m really out of ideas…

My environment:

$ node -v

$ npm -v