title: File operations doesn't work sometimes
body: <p>Something very strange is happenning in my app. I am creating 2 folders in the SD card if they not exist, and downloading some images from a URL if they not exist in the SD card. 
  Sometimes, when I run the application, the program checks if the folders exists and also the images, as they are exists, it continues and there's nothing wrong.
  But often when I run the application, it alerts me that the folders not exists and that it didn't even managed to create those folders, and afterwards I'm getting a "File not found exception" when it tries to download the images who already exists in my SD card.</p>
  
  <p>P.S: I tried it with 2 devices and the same happens, sometimes works, sometimes doesn't.</p>
  
  <p>What could be the problem here?</p>