I am trying to get homestead to work after following the instructions here
I have Virtualbox 5.0.6 and Vagrant 1.7.4 on windows 8. The machine boots up fine(ish) the on
sstarlight was on the right track. It's a path name issue. I'm on windows 8 with homestead too and you need to use the forward slashes even in your windows paths.
The below should do the trick!
authorize: C:/Users/Khalid/.ssh/id_rsa.pub
keys:
    - C:/Users/Khalid/.ssh/id_rsa
folders:
    - map: D:/work
      to: /home/vagrant/Code
sites:
    - map: homestead.app
      to: /home/vagrant/Code/Laravel/public
I would add to this that you should run the provisioning as per the other answer after you make the change by bringing your homestead up with the --provision flag set.
Make sure and re-verify that the path for the keys and authorize are correct and run vagrant up --provision to re-provision the homestead setup again
Try change
 D:\work to D:/work/