If you leave in the repository special char names like the ones I renamed bellow, he fixture load operation fail under Windows OS. Please3 verify if you don't beleive me ;)

Careful, database will be purged. Do you want to continue Y/N ?y
  > purging database
  > loading [1] Sonata\Bundle\DemoBundle\DataFixtures\ORM\LoadUserData
  > loading [2] Sonata\Bundle\DemoBundle\DataFixtures\ORM\LoadMediaData
  > loading [3] Sonata\Bundle\DemoBundle\DataFixtures\ORM\LoadNewsData
  > loading [4] Sonata\Bundle\DemoBundle\DataFixtures\ORM\LoadPageData
  > loading [10] Sonata\Bundle\DemoBundle\DataFixtures\ORM\LoadCollectionData
  > loading [11] Sonata\Bundle\DemoBundle\DataFixtures\ORM\LoadCategoryData
  > loading [12] Sonata\Bundle\DemoBundle\DataFixtures\ORM\LoadProductData

  [RuntimeException]
  The file does not exist : D:\www\sonata\site\src\Sonata\Bundle\DemoBundle\D
  ataFixtures\ORM/../data/files/hugo-canada\2010-06-24 a` 13-40-07.jpg

and the cloen was correctly created on disk.