I have a problem whereby any files uploaded into the private directory cannot be viewed - returning a 404 not found error. The images upload ok and get placed in sites/default/files/private directory. The image path when trying to view is in the form /system/files/image.jpg which I believe is correct.
Firstly I found that there are conflicts with the Fast 404 module. Disabling this module makes the private files now work on my staging server, but not on our live server.
Could there be any server-side settings that could be affecting this?
What else should I be checking?