Do the subfolders in data/media/... have the chmod 777 rights?
3) If the safe mode is turned off, and the problem still exists, or if the mod doesn´t work:
try to delete all the folders in /data/media/ (called /1 and /2 and so on: depends on the number of categories you´ve already created).
then create the folders by hand, name them 1 , 2 , 3 and so on.. don´t forget to set the folder rights (777).