I'm currently running ~150 Omeka installations on a dedicated server for a university project.
One group has a problem adding items: they just can't. For screenshots, please refer to: http://tranb300.ulb.ac.be/simon (before and after the error).
This happens when creating content, not even uploading or doing anything else. As far as I know, the other omeka installations work just fine (some groups have added content, pictures, *.pdf, etc). Not a server problem then.
In order to display the errors, I have edited the .htaccess and changes 'php_value display_errors' to 1 + application/config/config.ini to true.
Upon re-producing the error, no error message is displayed (only the screen you can see on the screenshot).
The "archive" folder is writable.
What should I do? Might it be that this particular Omeka installation is faulty? If yes, is there any way to repair it "automatically" (like a filecheck). Or is it possible (and easy) to export all the work already done by the students (collections, etc) to another omeka installation, and leaving this one "as is" for further inspection after the course is completed?