Description of my issue:
It appears to fail when trying to read file names that have Chinese as part of the file name.
The file has exactly the same "permissions" as all other files in the same directory.
I get this message (example) when I try and create a backup.
Unreadable file F:/wamp/www/hyccchina3/images/photo/?? DSC00331.JPG. Check permissions
Actual filename is "复件 DSC00331.JPG"
I got a LOT of these warning messages, across many subfolders within the image directory.
I don't recall getting this message before, with other (live) sites, running Joomla 2.5.
I hope it's just a stupid misconfiguration on my WAMP server...
I've attached the log file