3
Try changing permissions to 777, then delete. If that doesn't work, upload a blank text file with exactly the same name and extension (to overwrite the original), change to 777, then delete it.
I have also come across a couple of modules that have hidden files in folders that don't show up by default in some FTP apps. You then get the 'folder not empty' error when you try to delete the folder.
It's all good fun...
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