I'm having a strange problem with the images on my website (Drupal 7.19). After migrating the site from the testing to the production server we weren't able to see images we've uploaded. Since we're a closed community all the images are uploaded to the private folder, which perfectly works. The images are there in the folder.
But when we try to access the images (and if it's just showing them as thumbnails on the page) we get a "broken image" icon - they're not available, neither the thumbnails nor the large version. The Drupal log then says "Access denied" for the user "guest", for every logged in user, even me as administrator. If I try to open the image via the direct link (e.g. from the Drupal log) Drupal shows a login page and after I log in I can perfectly see the image.
So I find this rather strange and I don't know how I should fix this problem. Since we needed a tight security plan I installed several extra modules like "Content Access" and "Taxonomy Access Control". I wonder if it has something to do with that? Or with the new server?
Thanks for reading and I hope someone can help me! I'm already pretty desperate!
Have a nice day, Svenja
PS: Strangely I found another two warnings in the log immediately after I uploaded an image. Maybe this could be a clue? "Warning: session_start(): Cannot send session cookie" and: "Warning: session_start(): Cannot send session cache limiter" - maybe that's a clue? (I have no idea...)