On Windows be specific and use node to start webdriver

[sroe]

On Windows cmd.exe needs to start node first so you need to put this command inside the gruntfile config:
protractor_webdriver: {
options: {
command: 'node node_modules/protractor/bin/webdriver-manager start'
},
all: {
}
}

where node_modules/proctractor/bin/ points to your local protractor installation and starts as root from the path where gruntfile.js remains.

[RonaldTreur]

Yup, or better yet, fix this in the code since there are windows-only branches anyway.

[seckardt]

Fixed with commit 80c2ae2