Image uploader fails to display them while it upload files correctly

Hi!

During the last few days I realize that I can’t upload any new image to my wordpress. When I’ve examined why this fails I’ve discovered that while wordpress upload new files correctly, it renames them by adding some extra random letters so wordpress try to display an image which not exist at all.

The image doesn’t display nor in the dashboard either in the frontend, but if I grab the correct URL I can view it in the browser. Even I can edit this image with the wordpress image editor!!!.

I’ve tryied to disable all the plugins but it still fails. As I’m using iThemes Security plugin, I also delete all the .htaccess lines which this plugin add without any result.

My theme is build on Roots but doesn’t have any special code added to functions (only a few lines to create an extra widget sidebar).

Please, somebody can give me some advice on how to solve this strange issue?

Thanks in advance