The "Device Setting" used to be the first test on the main menu. Find it and run it to create the missing file (like it says). That file is needed to disable diags.
EDIT: Alternatively, you can export USB from the diags menu, and create the missing "diagnostic_logs/device_info.xml" file on the shared USB drive from the host PC.
Last edited by geekmaster; 09-13-2012 at 11:45 PM.