New Grunt user here who is using a lot of new tools (npm nodejs) today.
I\'ve got Grunt \"installed\" and have been able to create a grunt.js file using the init tas
SOLVED !!
So, this problem occur because windows by default associative < *.js > files with >> "Microsoft Windows Based Script Host".
grunt need to open by default with (grunt.cmd).
it easy to slove, by change default app (open with..)
Go to any javascript file with "js" extension. (any file)
Right-Click(mouse) > Properties > "Opens with:" Change...(button)
Choose Notepad ( or any javascript IDE ).
PROBLEM SOLVED ! :) good luck